Supervised Learning – EML https://enjoymachinelearning.com All Machines Learn Wed, 03 Apr 2024 17:04:20 +0000 en-US hourly 1 https://wordpress.org/?v=6.4.5 https://enjoymachinelearning.com/wp-content/uploads/2024/03/cropped-eml-header-e1709858269741-32x32.png Supervised Learning – EML https://enjoymachinelearning.com 32 32 Heuristic Algorithm vs Machine Learning [Well, It’s Complicated] https://enjoymachinelearning.com/blog/heuristic-algorithm-vs-machine-learning/ https://enjoymachinelearning.com/blog/heuristic-algorithm-vs-machine-learning/#respond Thu, 22 Feb 2024 22:53:40 +0000 https://enjoymachinelearning.com/?p=2359 Read more

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Today, we’re exploring the differences between heuristic algorithms and machine learning algorithms, two powerful tools that can help us tackle complex challenges in the complex world that we live in.

In a nutshell, heuristic algorithms are like shortcuts to finding solutions.

In contrast, machine learning algorithms are a systematic way for computers to learn from data and create optimized, all-encompassing solutions. 

While the above is just a simple introduction to these two, throughout the rest of this article, we will give you our formula for deciding which of the two you should use whenever a problem arises.

Trust us, by the end of this article; you’ll be the go-to expert among your friends. 

An Easy Example To Understand How A Heurstic Is Different Than An Algorithm

Let’s break down the differences between a heuristic and an algorithm with a simple, everyday example.

A heuristic approach would be to think about the typical spots where you usually put your keys on the kitchen counter, by the front door, or in your coat pocket.

Although there’s no guarantee that you’ll find your keys using this method, it’s a quick and practical way to start your search.

Most of the time, this technique will lead you to your missing keys in no time!

On the other hand, an algorithmic approach would be more systematic and thorough.

You’d start at one corner of your house and search every inch, moving from room to room until you find your keys.

This method has a 100% success rate (assuming your keys are actually in the house), but it could take a long time to complete.

So, in a nutshell, a heuristic is like an intelligent guess or shortcut that saves time, while an algorithm is a step-by-step process that guarantees a solution but might take longer.

Are Machine Learning Algorithms Heuristic Algorithms?

algorithms

From the example above, we hope you’ve now got a basic understanding of heuristics and algorithms – let’s talk about machine learning. 

You might be wondering: are machine learning algorithms heuristic algorithms? 

The answer is a little more complicated than it seems – remember their unique characteristics from above.

While both methods can be used to solve problems, machine learning algorithms focus on providing the best possible results under specific conditions. This is where they differ from heuristics.

Machine learning algorithms are designed to optimize performance and guarantee certain levels of accuracy, confined to their domain restrictions.

Each popular algorithm has its own set of guarantees for optimality, which is why we use them in different scenarios.

In other words, machine learning algorithms aim to deliver the best solution based on the available data.

Heuristics, on the other hand, don’t necessarily satisfy this premise.

They prioritize speed and simplicity, often leading to good-enough solutions rather than the best possible ones.

While heuristics can be effective in many situations, they may not always provide the optimal results that machine learning algorithms can achieve within the same restrictions.

Are Some Parts Of Machine Learning Heuristic In Nature?

When examining the inner workings of machine learning, it’s interesting to note that some aspects are indeed heuristic.

While the overall process relies on optimization and data-driven techniques, certain decisions made while developing a machine-learning model can be based on heuristics.

One example of a heuristic aspect in machine learning is the selection of input variables, also known as features.

These features are used to train the model, and choosing the right set is crucial for the model’s performance. 

The decision of which features to include or exclude is often based on domain knowledge and experience, making it a heuristic decision.

Another heuristic component in machine learning can be found in the design of neural networks.

A neural network’s topology or structure, including the number of layers and neurons in each layer, can significantly impact its performance.

While some guidelines exist for creating an effective neural network, the final design often comes down to trial and error, guided by heuristics (and intuition).

Maybe you notice that whenever someone buys graham crackers (my favorite), they also purchase marshmallows and Hershey chocolate bars. An obvious heuristic would be to suggest these products to customers together, 

However, using a machine learning algorithm to analyze customer behavior data and generate tailored shopping suggestions is a more advanced and accurate method, which would find much deeper relationships between item purchases.

Even so, certain heuristic decisions, like excluding irrelevant features such as the current outside temperature when building a model about financial decisions (as an example), will always play a role in developing a high-quality machine learning model.

Ultimately, the decision between heuristic algorithms and machine learning should be driven by a comprehensive understanding of the problem at hand, coupled with an awareness of the strengths and limitations inherent in each approach.

In many cases, a hybrid approach that combines the interpretability of heuristic algorithms with the predictive power of machine learning may offer the most effective solution.

Thus, rather than viewing heuristic algorithms and machine learning as competing paradigms, it is more fruitful to consider them as complementary tools in the data scientist’s toolkit, each serving a unique role in addressing complex real-world challenges.

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Pytorch Lightning vs TensorFlow Lite [Know This Difference] https://enjoymachinelearning.com/blog/pytorch-lightning-vs-tensorflow-lite/ https://enjoymachinelearning.com/blog/pytorch-lightning-vs-tensorflow-lite/#respond Thu, 22 Feb 2024 22:51:36 +0000 https://enjoymachinelearning.com/?p=2353 Read more

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In this blog post, we’ll dive deep into the fascinating world of machine learning frameworks – We’ll explore two famous and influential players in this arena: TensorFlow Lite and PyTorch Lightning. While they may seem like similar tools at first glance, they cater to different use cases and offer unique benefits.

Pytorch Lightning is a high-performance wrapper for Pytorch, providing a convenient way to train models on multiple GPUs. Tensorflow lite is designed to put pre-trained Tensorflow models onto mobile phones, reducing server and API calls since the model runs on the mobile device.

While this is just the general difference between the two, this comprehensive guide will highlight a few more critical differences between TensorFlow Lite and PyTorch Lightning to really drive home when and where you should be using each one.

We’ll also clarify whether PyTorch Lightning is the same as PyTorch and if it’s slower than its parent framework.

So, buckle up and get ready for a thrilling adventure into machine learning – and stay tuned till the end for an electrifying revelation that could change how you approach your next AI project!

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Understanding The Difference Between PyTorch Lightning and TensorFlow Lite

Before we delve into the specifics of each framework, it’s crucial to understand the fundamental differences between PyTorch Lightning and TensorFlow Lite.

While both tools are designed to streamline and optimize machine learning tasks, they serve distinct purposes and cater to different platforms.


PyTorch Lightning: High-performance Wrapper for PyTorch

PyTorch Lightning is best described as a high-performance wrapper for the popular PyTorch framework.

It provides an organized, flexible, and efficient way to develop and scale deep learning models.

With Lightning, developers can leverage multiple GPUs and distributed training with minimal code changes, allowing faster model training and improved resource utilization.

gpu

This powerful tool simplifies the training process by automating repetitive tasks and eliminating boilerplate code, enabling you to focus on the core research and model development.

Moreover, PyTorch Lightning maintains compatibility with the PyTorch ecosystem, ensuring you can seamlessly integrate it into your existing projects.


TensorFlow Lite: ML on Mobile and Embedded Devices

On the other hand, TensorFlow Lite is a lightweight, performance-optimized framework designed specifically for deploying machine learning models on mobile and embedded devices.

It enables developers to bring the power of AI to low-power, resource-constrained platforms with limited internet connectivity.

TensorFlow Lite relies on high-performance C++ code to ensure efficient execution on various hardware, including CPUs, GPUs, and specialized accelerators like Google’s Edge TPU.

It’s important to note that TensorFlow Lite is not meant for training models but rather for running pre-trained models on mobile and embedded devices.


What Do You Need To Use TensorFlow Lite

To harness the power of TensorFlow Lite for deploying machine learning models on mobile and embedded devices, there are a few essential components you’ll need to prepare. 

Let’s discuss these prerequisites in detail:


A Trained Model

First and foremost, you’ll need a trained machine-learning model.

This model is usually developed and trained on a high-powered machine or cluster using TensorFlow or another popular framework like PyTorch or Keras.

The model’s architecture and hyperparameters are fine-tuned to achieve optimal performance on a specific task, such as image classification, natural language processing, or object detection.

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Model Conversion

Once you have a trained model, you must convert it into a format compatible with TensorFlow Lite.

The conversion process typically involves quantization and optimization techniques to reduce the model size and improve its performance on resource-constrained devices.

TensorFlow Lite provides a converter tool to transform models from various formats, such as TensorFlow SavedModel, Keras HDF5, or even ONNX, into the TensorFlow Lite FlatBuffer format.

More information on it can be found here.


Checkpoints

During the training process, it’s common practice to save intermediate states of the model, known as checkpoints.

Checkpoints allow you to resume training from a specific point if interrupted, fine-tune the model further, or evaluate the model on different datasets. 

When using TensorFlow Lite, you can choose the best checkpoint to convert into a TensorFlow Lite model, ensuring you deploy your most accurate and efficient version.


When would you use Pytorch Lightning Over Regular Pytorch?

While PyTorch is a compelling and flexible deep learning framework, there are specific scenarios where using PyTorch Lightning can provide significant benefits.

Here are a few key reasons to consider PyTorch Lightning over regular PyTorch:


Minimize Boilerplate Code

Developing deep learning models often involves writing repetitive and boilerplate code for tasks such as setting up training and validation loops, managing checkpoints, and handling data loading.

PyTorch Lightning abstracts away these routine tasks, allowing you to focus on your model’s core logic and structure.

This streamlined approach leads to cleaner, more organized code that is easier to understand and maintain throughout a team of machine learning engineers.

Python Code


Cater to Advanced PyTorch Developers

While PyTorch Lightning is built on top of PyTorch, it offers additional features and best practices that can benefit advanced developers.

With built-in support for sophisticated techniques such as mixed-precision training, gradient accumulation, and learning rate schedulers, PyTorch Lightning can further enhance the development experience and improve model performance.


Enable Multi-GPU Training

Scaling deep learning models across multiple GPUs or even multiple nodes can be a complex task with regular PyTorch.

PyTorch Lightning simplifies this process by providing built-in support for distributed training with minimal code changes.

This allows you to leverage the power of multiple GPUs or even a cluster of machines to speed up model training and reduce overall training time.


Reduce Error Chances in Your Code

By adopting PyTorch Lightning, you can minimize the risk of errors in your code due to its structured approach and automated processes.

Since the framework handles many underlying tasks, you’ll be less likely to introduce bugs related to training, validation, or checkpoint management – Think about it, with Pytorch Lightning, you’ll actually be writing less code – and when you’re writing less code – you’ll naturally make fewer errors.

Additionally, the standardized design of PyTorch Lightning promotes code reusability and modularity, making it easier to share, collaborate, and troubleshoot your models.

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High Accuracy Low Precision Machine Learning [What THIS Means] https://enjoymachinelearning.com/blog/high-accuracy-low-precision-machine-learning/ https://enjoymachinelearning.com/blog/high-accuracy-low-precision-machine-learning/#respond Thu, 22 Feb 2024 21:57:01 +0000 https://enjoymachinelearning.com/?p=2266 Read more

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One of the most important things in machine learning is evaluating how well your model is doing.

Two important metrics for this are accuracy and precision.

Sometimes, a machine learning model might have high accuracy but low precision.

This can be misleading to the machine learning engineer, as a high accuracy score might make you think the model works well when it may need improvement.

High accuracy and low precision mean that the classification algorithm is making a lot of correct predictions. Still, it’s missing predictions on a key group of values, meaning you have a high rate of false positives. 

This article will explain what high accuracy and low precision mean and why you shouldn’t outright trust it.

We’ll also walk you through how to improve your machine-learning model process, where you’re not just blindly trusting metrics.

Get ready to take your machine-learning skills to the next level!

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What is the Difference Between Accuracy And Precision?

Before jumping right into what high accuracy and low precision mean together, we need to understand what each means individually.

Accuracy is all about how many times the model gets it right. 

It’s like a math test in school – if you get 80% of the answers right, then your accuracy is 80%. 

Simple, right?

Precision is a little bit different.

Precision is about being specific and getting the right answer for the right thing.

do the right thing

For example, if you’re again taking a math test and get all the geometric answers correct but miss some from another category, you had high precision with geometry but low on that other category.

So in machine learning, precision is slightly different but still uses that same idea.

While precision in the real world can relate to anything, precision within machine learning focuses on one thing and one thing only, false positives.

A high precision rate means you have few to no false positives, but a low precision means you have many false positives.

In short, accuracy is about getting the right answer, and precision is about getting the right answer for the right thing.

What Does High Accuracy Low Precision Mean During Machine Learning?

Simply, High accuracy and low precision mean that the classification algorithm is making a lot of correct predictions. Still, it’s missing predictions on a key group of values, meaning you have a high rate of false positives. 

For a dataset to have high accuracy and low precision, it usually means there’s a low amount of true positives within the dataset.

Since your algorithm can predict everything accurately but has a high false positive rate, you need low amounts of true positives relative to the total rows of data to make this happen.

This means you’ll see this type of thing in datasets with a low “hit” rate, like medical diagnosis, error detection, candidate hiring, etc.

Before you freak out about high accuracy and low precision, we’ll review type I and type II errors in the next section.

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Understanding Type I and Type II Error

Remember, In machine learning, our model will make some mistakes; it’s part of the game.

However, all errors made aren’t isn’t equal.

There are two different types of mistakes that models can make: Type I and Type II errors.

A Type I error is a false-positive that we’ve been talking about. 

It’s when the model says something is wrong, but it’s not. For example, if a fire alarm goes off without fire, that’s a Type I Error.

Type II Error is a false-negative, where we’ve mislabeled an occurring positive event. 

For example, if a fire alarm doesn’t go off when there is a fire, that’s a Type II Error.

A well-known secret around the machine learning industry is that these “Errors” are rarely equal.

secret

While it is a bit complicated not to think of errors as equal, it’s easiest to understand with an example.

When Google hires engineers, they spend a ton of money ensuring they don’t hire the wrong candidate. Since a bad hire can corrupt a whole department, they’d rather decline candidates that are on the line (probably good enough) to ensure they don’t accidentally hire any wrong candidates.

In this scenario, google will have many Type II errors (false negatives from declining good candidates), but they’ve already accepted this.

What they’re trying to optimize is having very few Type I errors (hiring the wrong engineer).

With a deep understanding of their business problem, they can utilize errors in a way that allows them to reach their desired outcome.

You need to understand your business problem in the same type of way. 

In some scenarios, when you classify, it makes much more sense to optimize on fewer false positives than it does to increase things like accuracy.

How Do We Decide Which Modeling Metric We Want To Improve?

As discussed in the section above, the first step to understanding your modeling metrics is fully understanding your business problem.

Does your business problem call for you to be right about everything, right about a specific subset of information, or not to be wrong about some particular instance of your dataset?

For example, high accuracy is generally useless when building a medical diagnosis model. 

medical team

This is because the occurrence of an event is so rare; even if you’re machine learning model predicts “No” on everything, it would still be right in the 90%+ percentile! (This is a common interview question in data science interviews, BTW).

Instead, focusing on something like recall, which is the split of samples we could identify in the positive class correctly, would be a much more impactful calculation.

Anyone who tells you there’s a one-fit-all modeling metric is lying, and things like F1 score, precision, recall, and accuracy all have their place when building out machine learning models.

Should I Always Fix Unbalanced Datasets

When calculating these advanced modeling metrics, a tip is to note the split in your dataset.

If you have way more positive events than negative events (1 vs. 0), this is known for leading to some misleading metrics.

Like everything else in this article, there is no strict “rule” regarding unbalanced datasets.

Personally, when it comes to any modeling question, I always leave it up to cross-validation.

Balance out your dataset, test it with cross-validation, and see if that beats not balancing it.


Other Articles In Our Accuracy Series:

Accuracy is used EVERYWHERE, which is fine because we wrote these articles below to help you understand it

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How Can Data Science Improve The Accuracy Of A Simulation?? [Heres How] https://enjoymachinelearning.com/blog/how-can-data-science-improve-the-accuracy-of-a-simulation-heres-how/ https://enjoymachinelearning.com/blog/how-can-data-science-improve-the-accuracy-of-a-simulation-heres-how/#respond Thu, 22 Feb 2024 21:51:15 +0000 https://enjoymachinelearning.com/?p=2304 Read more

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Data Science is a field of study that uses mathematics, statistics, and computer science to analyze and make sense of large amounts of data – which is perfect since it can also be used to improve simulations.

Think of a simulation as a virtual representation of a real-life scenario. 

Simulation is used in basically every field, such as engineering, science, and finance. 

Using data science techniques, we can better understand the data used in our simulations, leading us to better outputs. We can make simulations even more accurate and reliable by taking advantage of data science.

Whether you’re a student, a scientist, or just someone interested in making your simulations a bit more accurate, you’ll learn something new and valuable from this post. 

So let’s jump right in!

jump in


What Exactly Is A Simulation?

A simulation is a virtual representation of a real-life scenario.

It’s like a model of a real-world situation, but it exists in a computer or a virtual environment. Think about a video game highly representative of the real world since it was built with statistics of the world behind it.

The goal of a simulation is to make the simulation as close as possible to what might actually happen in real life. 

For example, if you wanted to know what would happen if you added an extra person to a line at the airport, you could create a simulation to study that specific situation. This would help you understand how the line would change anything and everything relevant to the line and what secondary effects it might have.

They allow us to study and analyze real-world scenarios without physically carrying out the experiment or situation.

This saves time, money, and resources and allows us to study situations that might be too dangerous, difficult, or expensive to study in real life.

saving money in jar


How Can Data Science Improve The Accuracy Of A Simulation?

Data science can be a valuable tool for improving the accuracy of simulations.

Using everyday data science techniques, we can get more accurate simulation inputs and better understand the outputs.

Here’s how:


Accurate Inputs

Data science techniques can be used to extract highly accurate and relevant distributions and rates from data.

This is perfect because you’ll need data if you plan to do any simulations.

This extracted information can then be directly plugged into our simulations, creating more accurate – and thus more representative – simulations. 

For example, suppose we were trying to simulate traffic movement in a city. In that case, data science could help us gather data on traffic patterns, road conditions, and other factors that highly affect the simulation.

traffic

Think about it this way, if you were given a very messy dataset, how would you find the numbers needed to supply your simulation?

To get these, you’d pull directly from data science techniques, allowing you to quickly find the patterns and distributions in your data to build your simulation model.


Fake Data

Data science can also be used to create fake or synthetic data for simulations. This can be especially useful when actual data is unavailable, too difficult, or expensive to collect.

Using statistical methods, machine learning algorithms, predictive analytics, and correlation to compute and predict new values, data scientists can generate synthetic data that highly resembles high-quality data. 

This synthetic data can then be used in simulations to test and evaluate different scenarios for which data scientists can’t find relevant data. 

For example, suppose we were trying to simulate the spread of a disease in a population. In that case, data science could help us generate synthetic data on the population’s demographics, health status, and movement patterns – without needing the actual “real” population data.

people

This synthetic data could then be used in the simulation to study how the disease might spread under different conditions.

The benefit of using synthetic data is that it allows us to create simulations without relying on actual data.

This can also save time, money, and resources, allowing us to study situations that might be too dangerous, complex, highly unique, or expensive to study in real life.


Handle Large Data

Data science can be a valuable tool for improving the accuracy of simulations by allowing us to process high amounts of data.

With the help of data science techniques, we can analyze and make sense of large amounts of data, which can be used in simulations to create more accurate simulations of real-world scenarios.

For example, suppose we were trying to simulate adding a new bank in a city. In that case, data science could help us gather data on other banks, spending habits, and other factors that would have a noticeable effect on the simulation.

bank

With this information, we could create a more accurate simulation of money flow in the city and even simulate other things like adding a couple of banks or a new restaurant. 


Understanding Outputs

Data science can also help us better understand the outputs of simulations.

While data is hard to understand, data science techniques show us what to look for in data, giving us an almost end goal to the data received from our simulations.

By analyzing the simulation results, we can identify patterns and trends and make more informed decisions about improving the simulation.


Another Avenue

Data science can help create more accurate simulations by literally allowing us to generate more simulations. 

While most receive their simulation values and have to be happy with them, Data science techniques, such as machine learning algorithms and statistical methods, can help us quantify new avenues and angles from our data, leading us to create more simulations.


Does Accuracy Matter In A Simulation?

Accuracy matters in simulations because it helps us make better decisions and predictions. 

By creating simulations that are as close as possible to what might happen in real life, we can better understand the situation and make more informed decisions about improving it.

In most fields, such as engineering, science, and finance, accuracy is critical since the difference of inches or percentages has a massive effect on the world around us.


Why Do We Need Simulations, If We Have Data Science?

Data science and simulations are tools that fall under the umbrella of statistics, and they have unique benefits and purposes.

Data science can be used to analyze and make sense of large amounts of data, and it provides us with answers/predictions for one point in time.

For example, if we were trying to understand how many people in a city use the public restroom, data science could quickly predict the whole year (if you had the data).

However, simulations allow us to see how things change over time. 

They visually represent a real-life scenario and help us understand how things might change or evolve. 

If we were trying to understand how traffic might build up in a city in the future, we could use a simulation to study the situation. This would help us understand how the traffic might change over time and what might happen when certain conditions change.

In short, we need simulations because they allow us to see how things change, while data science provides answers for one point in time. Both data science and simulations are valuable tools in the field of statistics, and they can be used together to understand real-world scenarios better.

 

Other Articles In Our Accuracy Series:

Accuracy is used EVERYWHERE, which is fine because we wrote these articles below to help you understand it

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Machine Learning: High Training Accuracy And Low Test Accuracy https://enjoymachinelearning.com/blog/machine-learning-high-training-accuracy-and-low-test-accuracy/ https://enjoymachinelearning.com/blog/machine-learning-high-training-accuracy-and-low-test-accuracy/#respond Thu, 22 Feb 2024 21:39:30 +0000 https://enjoymachinelearning.com/?p=2290 Read more

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Have you ever trained a machine learning model and been really excited because it had a high accuracy score on your training data.. but disappointed when it didn’t perform as well on your test data? (We’ve all been there)

This is a common problem that ALL data scientists face. 

But don’t worry; we know just the fix! 

In this post, we’ll talk about what it means to have high training accuracy and low test accuracy and how you can fix it. 

However, we want to emphasize that this is probably the wrong approach towards your modeling methods, and another technique could give you a much better insight into your modeling experience.

So, stay tuned and get ready to become an expert in machine learning!

pro in ml


Why Do We Need To Score Machine Learning Models?

Like in sports, where you keep score to track how you’re doing, in machine learning, we also need to score our models to see how well they perform.

This is important because you need to track your model’s performance to know if it’s making any decent predictions.

And to Score our Models, we use a thing called metrics. 

Metrics are tools that help machine learning engineers and data scientists measure the performance of our models. 

There are TONS of different metrics, so it’s essential to understand which metrics are best for your problem.

Hint, accuracy is not always the best fit!

top tips

For example, if you’re building a model to predict whether a patient has a particular disease, you might use metrics like accuracy, precision, and recall to measure its performance.

On the other hand, if you’re building a model to predict the price of a house, you might use metrics like mean absolute error or root mean squared error.


What Does High Training Accuracy and Low Test Accuracy Mean?

When you train a machine learning model, you split your data into training and test sets.

The model uses the training set to learn and make predictions, and then you use the test set to see how well the model is actually performing on new data.

If you find that your model has high accuracy on the training set but low accuracy on the test set, this means that you have overfit your model. 

Overfitting occurs when a model too closely fits the training data and cannot generalize to new data.

In other words, your model has memorized the training data but fails to predict on data accurately it has yet to see.

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This can have a few different causes.

First, It could simply mean that accuracy isn’t the right metric for your problem. 

For example, suppose you’re building a model to predict whether a patient has a certain disease. In that case, accuracy might not be the best metric to use because you want to be sure that you catch all instances of the disease, even if that means having some false positive results. In scenarios like this, accuracy can be biased due to your dataset’s low amounts of actual true positives.

Another cause of high training and low test accuracy is simply needing a better model. This could be because your model is too complex or because it’s not capturing the underlying patterns in the data.

In this case, you should try a different model or change the model parameters you’re using.


Should Training Accuracy Be Higher Than Testing Accuracy?

In machine learning, it’s typical for the training accuracy to be a bit higher than the testing accuracy. This is because the model uses the training data to make predictions, so it’s expected to perform slightly better on the training data.

However, if the difference between the training and testing accuracy is too significant, this could indicate a problem. 

You generally want the difference between the training and testing accuracy to be as small as possible. If the difference is too significant, it could mean your model is not performing well on new data and needs improvement.

It’s important to remember that slight overfitting is impossible to avoid entirely. However, if you see a large difference between the training and testing accuracy, it’s a sign that you may need to make changes to your model or the data you’re using to train it.

However, in the next section, I argue that you should completely change how you do this WHOLE process.

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Should I Even Be Testing My Model This Way?

When building a machine learning model, you’ve probably been told a thousand times that it’s essential to split your data into a training set and a test set to see how well your model is performing. (This is called a train test split)

However, a train test split only uses a single random subset of your data as the test set…

This means that you’re only getting a single score for your model, which might not represent how your model would perform over all of the data.

Think about it this way, what if you tested a different “test” set from your model and got a completely different score, which is the one you’d report to your manager?

thinking


Cross Validation is Superior To Train Test Split

Cross-validation is a method that solves this problem by giving all of your data a chance to be both the training set and the test set.

In cross-validation, you split your data into multiple subsets and then use each subset as the test set while using the remaining data as the training set. This means you’re getting a score for your model on all the data, not just one random subset.

The score from cross-validation is a much better representation of your model’s performance than a single-train test split score.

This is because the cross-validation score is the average test score from each subset of your entire dataset, not just one random part. 

This gives you a more accurate picture of how well your model is actually performing and helps you make better decisions about your model.

thumbs up in an office

Can you always use Cross Validation?

Cross Validation can only be used in independent data. This means things like time-series data or other non-independent data are off-limits for cross-validation. While you can write a book on this topic (and we won’t cover it here), we wanted to emphasize this before Cross Validation becomes your only go-to modeling method. 

 

Other Articles In Our Accuracy Series:

Accuracy is used EVERYWHERE, which is fine because we wrote these articles below to help you understand it

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Machine Learning: Validation Accuracy [Do We Need It??] https://enjoymachinelearning.com/blog/machine-learning-validation-accuracy/ https://enjoymachinelearning.com/blog/machine-learning-validation-accuracy/#respond Thu, 22 Feb 2024 21:35:40 +0000 https://enjoymachinelearning.com/?p=2317 Read more

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Validation Accuracy, in the context of machine learning, is quite a weird subject, as it’s almost the wrong way of looking at things.

You see, there are some particular deep-learning problems (neural networks) where we need an extra tool to ensure our model is “getting it.”

For this, we usually utilize a validation set.

However, this validation set is usually used to improve model performance in a different way instead of emphasizing the accuracy of the machine learning model.

While that may seem confusing, we will clear everything up below. We’ll look closer at validation accuracy and how it’s different ideologically from training and testing accuracy.

We’ll also share some cool insights that’ll make you a machine-learning whiz in no time. 

So, buckle up and get ready to learn something amazing!

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What’s The Difference Between Validation Accuracy And Testing Accuracy?

As we dive deeper into machine learning, it’s essential to understand the distinction between validation and testing accuracy. 

At first glance, the difference may seem simple: validation accuracy pertains to the validation set, while testing accuracy refers to the test set.

However, this superficial comparison doesn’t capture the true essence of what sets them apart.

In reality, the validation set plays a unique role in the machine learning process.

It’s primarily used for tasks like assessing the performance of a model’s loss function and monitoring its improvement. The validation set also helps us determine when to halt the training process, a technique known as early stopping. 

By contrast, the test set is used to evaluate a model’s performance in a more comprehensive manner, providing a final accuracy score that indicates how well the model generalizes to unseen data.

In other words, while the validation set helps us fine-tune our model during training, the test set is our ultimate measuring stick.

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We can obtain a true accuracy score only when we utilize the test set, which tells us how well our model will likely perform when faced with real-world challenges.

You can safely report this accuracy score to your boss, not the one from the training or validation set.

Understanding the nuances between validation and testing datasets is crucial for anyone delving into machine learning. 

By recognizing their distinct roles in developing and evaluating models, we can better optimize our approach to training and testing, ultimately leading to more accurate and robust machine learning solutions.


Do I Even Need A Validation Set?

When building our models, we must ask ourselves whether a validation set is always necessary. 

To answer this question, let’s first consider the scenarios where validation sets play a crucial role.

Validation datasets are predominantly used in deep learning, mainly when working with complex neural networks.

These networks often require fine-tuning and monitoring during the training process, and that’s where the validation set steps in.

However, it’s worth noting that deep learning is just a slice of the machine learning spectrum.

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In fact, about 90%+ of machine learning problems (This number is from personal experience) are tackled through supervised learning.

In these cases, validation sets don’t typically play any role.

This might lead you to believe only training and test sets are needed for supervised learning.

While that’s true to some extent, there’s an even better technique to ensure you thoroughly understand your model’s performance is cross-validation.

Cross-validation is a robust method that involves dividing your dataset into multiple smaller sets, or “folds.”

You then train your model on a combination of these folds and test it on the remaining one.

This process is repeated several times, with each fold serving as the test set once.

By using cross-validation, you can obtain a more accurate and reliable estimation of your model’s performance.


Does Cross Validation Use A Validation Set?

While we now know that cross-validation is perfect for supervised learning, It’s natural to wonder how cross-validation fits into the bigger picture, especially when using validation sets. 

Simply put, if you’re using cross-validation, there’s no need for a separate validation set.

To understand why, let’s first recap what cross-validation entails. During this process, your dataset is divided into several smaller sets, or “folds.” The model is then trained on a combination of these folds and tested on the remaining one. This procedure is repeated multiple times, with each fold taking its turn as the test set.

Essentially, cross-validation ensures that each piece of data is used for both training and testing at different times.

Introducing a separate validation dataset doesn’t make sense in this context. In cross-validation, the data already serves the purpose of training and testing, eliminating the need for an additional validation set.

By leveraging the power of cross-validation, you can obtain a more accurate and reliable estimation of your model’s performance without the added complexity of a validation dataset.

high accuracy


Can Validation Accuracy Be 100%?

So, let’s say you’ve encountered scenarios or an epoch where your model’s validation accuracy reaches a seemingly perfect 100%. 

Is this too good to be true? 

Let’s explore some factors to consider when encountering such “extraordinary results.”

First and foremost, it’s important to determine whether this 100% validation accuracy is a one-time occurrence during the training process or a consistent trend.

If it’s a one-off event, it may not hold much significance.

However, if you’re consistently achieving high scores on your predictions, it’s time to take a look at your validation set more closely.

It’s crucial to ensure that your validation set isn’t silently biased.

For example, in a deep learning classification problem, you’ll want to verify that your validation data doesn’t exclusively represent one category. 

bias


This could lead to an illusion of perfection, while in reality, your model may not be generalizing well to other categories.

Finally, remember that accuracy isn’t always the best metric to evaluate your model.

Other metrics such as precision, recall, or F1-score might be more suitable depending on the problem at hand – especially in the context of problems trying to solve for “rare events.”

Solely relying on accuracy could falsely assess your model’s actual performance.

And thus make the machine learning engineer behind it look a bit silly.


What Percentage Should Of Our Data Should The Validation Set Be?

Determining the ideal percentage of data to allocate for the validation set can be a perplexing task.

If you don’t live under a rock, You may have encountered standard rules of thumb like “use 10%!”

However, these one-size-fits-all guidelines can be shortsighted and may only sometimes apply to some situations.

The truth is, the best percentage for your validation set depends on your specific dataset.

Although there is no universally applicable answer, the underlying goal remains the same: you want your training dataset to be as large as possible.

This principle is based on the idea that the quality of your training data directly impacts the performance of your algorithm. And as you might already know, one of the most straightforward ways to enhance your training data is to increase its size.

More data allows your model to learn better patterns, which leads to improved generalization (less overfitting) when faced with new, unseen data.

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Other Articles In Our Accuracy Series:

Accuracy is used EVERYWHERE, which is fine because we wrote these articles below to help you understand it

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Vector Autoregression vs ARIMAX [This Key Difference] https://enjoymachinelearning.com/blog/vector-autoregression-vs-arimax/ https://enjoymachinelearning.com/blog/vector-autoregression-vs-arimax/#respond Thu, 22 Feb 2024 21:31:55 +0000 https://enjoymachinelearning.com/?p=2344 Read more

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In time series analysis, selecting the right model for forecasting can be challenging.

Two popular models often competing for the spotlight are Vector Autoregression (VAR) and Autoregressive Integrated Moving Average with Exogenous Variables (ARIMAX).

Both models have their unique strengths, but the choice ultimately depends on the structure of your data and the type of problem you’re trying to solve.

The main difference between the two is their ability to handle multiple time series: VAR is built for multivariate time series analysis, while ARIMAX focuses on univariate time series with exogenous variables.

Below, we’ll go more in-depth on the VAR and ARIMAX models, discuss some differences between moving averages and autoregressive formulation and explain some of the tough-to-understand terms used above.

You’re not going to want to miss this one. 

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Differences Between Autoregression and Moving Average

Understanding the difference between Autoregression (AR) and Moving Average (MA) is essential when diving into the world of time series analysis.

Let’s break down these concepts in a way that everyone can understand.

Autoregression (AR) is about using the past values, or “lags,” of a time series to predict future values.

Imagine you’re trying to forecast the temperature for tomorrow. If you know that today’s temperature was 75 degrees and yesterday’s was 72 degrees, you could use this information to make a prediction.

In other words, AR models rely on the idea that the past can help predict the future.

Predict the future

Moving Average (MA), however, is focused on the errors, or “error lags,” in the time series. Let’s say you tried to predict the temperature for yesterday and made an error in your forecast.

An MA model would look at your past errors to help better predict today and tomorrow. This way, the model learns from its mistakes and improves its forecasting ability over time – based on the assumption that errors have some trend.

Understanding the difference between these two forecasting ideologies is HUGE when trying to understand the difference between ARIMAX and VAR.

One Vs. Many

Before we continue diving into the differences between VAR and ARIMAX, we must understand the terms “multivariate” and “univariate.”

In time series analysis, “multivariate” means working with multiple time series simultaneously, while “univariate” means focusing on just one time series. 

Now, let’s explore how VAR and ARIMAX are designed for these different situations.

Vector Autoregression (VAR) is designed explicitly for multivariate time series analysis.

This means it can handle multiple time series that might be related to each other.

For example, if you wanted to forecast the prices of several stocks in the market, a VAR model could consider how the prices of these stocks influence each other over time.

This makes VAR a powerful tool for understanding complex relationships between multiple time series.

On the other hand, Autoregressive Integrated Moving Average with Exogenous Variables (ARIMAX) is built for univariate time series analysis, which means it focuses on just one time series.

However, it has an added twist: it can incorporate exogenous variables. 

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Exogenous variables are simply just external factors that might affect the time series but aren’t part of it. 

For instance, if you were forecasting the sales of a particular product, you might want to consider factors like the price, advertising campaigns, or even the weather. These external factors can help improve the accuracy of the ARIMAX model’s forecasts.

Is VAR better than Arimax?

Asking if Vector Autoregression is better than ARIMAX is the wrong way to think about things.

Deciding between (VAR) and ARIMAX mostly depends on the specific problem you’re working on and the nature of your data. 

Each model has advantages; the best choice depends on your unique situation.

Let’s review some factors to consider when choosing between VAR and ARIMAX:

The number of time series

If you are dealing with interconnected time series, VAR is the better choice because it is designed for multivariate analysis. On the other hand, if you are working with a single time series, ARIMAX would be more appropriate.

Exogenous variables

If external factors influence your time series, ARIMAX is useful because it allows you to incorporate these exogenous variables. VAR does not have this feature, so if exogenous variables are critical to your analysis, ARIMAX may be the better choice.

Model complexity

VAR models can become quite complex when dealing with multiple time series, which may require more computational power and time to estimate. If you need a simpler model and have only one time series to analyze, ARIMAX might be more suitable.

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Interpretability

ARIMAX models can be easier to interpret when dealing with exogenous variables, as you can directly see the impact of these external factors on your time series. In contrast, VAR models focus on the relationships between multiple time series, which can be more challenging to understand and explain.

Are Arimax and VAR the only two Time Series Models?

While ARIMAX and VAR are popular time series models, they are not the only options for time series analysis. There is a wide variety of models to choose from, each with its strengths and weaknesses. Here are a few other common time series models to consider:


Autoregressive (AR) model

This univariate model uses the time series’s past values, or lags, to make predictions. It is a simpler version of ARIMAX without the integrated moving average or exogenous variables components.


Moving Average (MA) model

Another univariate model, the MA model, focuses on past errors, or error lags, to improve its forecasting ability.


Autoregressive Integrated Moving Average (ARIMA) model

Combining the AR and MA models, the ARIMA model also accounts for differencing to make the time series stationary. It is essentially an ARIMAX model without exogenous variables.


Seasonal Decomposition of Time Series (STL)

This technique breaks down a time series into its trend, seasonal, and residual components. It can help analyze time series with strong seasonality.


Exponential Smoothing State Space Model (ETS)

This family of models includes simple, double, and triple exponential smoothing, which can be used for forecasting univariate time series with different levels of trend and seasonality.


Long Short-Term Memory (LSTM) networks

These are a type of recurrent neural network designed explicitly for sequence data, such as time series. They can be helpful for complex problems and large datasets where traditional time series models may struggle. (Ever Heard of ChatGPT?)

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Lasso Regression vs PCA [Use This Trick To Pick Right!!] https://enjoymachinelearning.com/blog/lasso-regression-vs-pca/ https://enjoymachinelearning.com/blog/lasso-regression-vs-pca/#respond Thu, 22 Feb 2024 21:22:52 +0000 https://enjoymachinelearning.com/?p=2378 Read more

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If you’re trying to understand the main differences between lasso regression and PCA – you’ve found the right place. In this article, we will go on a thrilling journey to learn about two cool data science techniques: Lasso Regression and PCA (Principal Component Analysis). While these two concepts may sound a bit complicated – don’t worry; we’ll break them down in a fun and easy way! 

The main difference between PCA and Lasso Regression is that Lasso Regression is a variable selection technique that deals with the original variables of the dataset. In contrast, PCA (Principle Component Analysis) deals with the eigenvectors created from the covariance matrix of the variables.

While the above makes it seem pretty simple – there are a few nuances to this difference that we will drive home later in the article.

If you’re trying to learn about these two topics, when to use them, or what makes them different, this article is perfect for you.

Let’s jump in.

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When You Should Use Lasso Regression

Lasso Regression is an essential variable selection technique for eliminating unnecessary variables from your model.

This method can be highly advantageous when some variables do not contribute any variance (predictability) to the model. Lasso Regression will automatically set their coefficients to zero in situations like this, excluding them from the analysis. For example, let’s say you have a skiing dataset and are building a model to see how fast someone goes down the mountain. This dataset has a variable referencing the user’s ability to make basketball shots. This obviously does not contribute any variance to the model – Lasso Regression will quickly identify this and eliminate these variables.

Since variables are being eliminated with Lasso Regression, the model becomes more interpretable and less complex.

Even more important than the model’s complexity is the shrinking of the subspace of your dataset. Since we eliminate these variables, our dataset shrinks in size (dimensionality). This is insanely advantageous for most machine learning models and has been shown to increase model accuracy in things like linear regression and least squares.

While Lasso Regression shares similarities with Ridge Regression, it is important to distinguish their differences.

lasso regression


Both methods apply a penalty to the coefficients to reduce overfitting; however, Lasso employs an absolute value penalty, while Ridge uses a squared penalty.

This distinction leads to Lasso’s unique variable elimination capability.

One crucial aspect to consider is that Lasso Regression does not handle multicollinearity well.

Multicollinearity occurs when two or more highly correlated predictor variables make it difficult to determine their individual contributions to the model.

In such cases, Lasso Regression might not be the best choice. 

Nonetheless, when working with data that has irrelevant or redundant variables, Lasso Regression can be a powerful and efficient technique to apply.


When You Should Use PCA

PCA is a powerful feature selection technique, though it is one of the most unique ones of the bunch. 

PCA is handy when dealing with many variables that exhibit high correlation or when the goal is to reduce the complexity of a dataset without losing important information.

While PCA does not eliminate variables like Lasso Regression, it does transform the original set of correlated variables into a new set of uncorrelated variables called principal components (linear combination).

This transformation allows for preserving as much information as possible while reducing the number of dimensions in the data.

By extracting the most relevant patterns and trends from the data, PCA allows for more efficient analysis and interpretation. 

Since you’ll be modeling over the eigenvectors, PCA gives you complete control (much like the lambda in Lasso) to decide how much of the variance you want to keep.

Usually, the eigenvectors will contribute to the variance with something like this.

 Eigen Vector 1 (Highest Corresponding Eigen Value)  50.6% of the total variance  
 Eigen Vector 2 (Second Highest Corresponding Eigen Value)  18.5% of the total variance  
 Eigen Vector 3 (Third Highest Corresponding Eigen Value)  15% of the total variance  
 Eigen Vector 4 (Fourth Highest Corresponding Eigen Value)  11% of the total variance  
 Eigen Vector 5 (Fifth Highest Corresponding Eigen Value)  4.9% of the total variance  

 Due to our covariance matrix’s “box” shape, we’ll have the same amount of eigenvectors as variables.

However, as we can see from above, we can drop eigenvector 5 (a 20% reduction in data size!) while only losing out on 4.9% of the total variability of the dataset.

Before utilizing PCA, we would have had to drop one of the variables, losing 20% of the variability for a 20% reduction in the dataset (assuming all variables contributed equally).

You should use PCA when you have many variables but don’t want to eliminate any original variables or reduce their input into the model. This is common in DNA sequencing, where thousands of variables contribute equally to something.

Note: Since PCA is trained on the eigenvectors, you’ll have to apply this same transformation to all data points before predicting in production. While this may seem like a huge hassle, saving and applying the transformation within your pipeline is very easy.


PCA vs Lasso Regression

As we’ve seen above, both Lasso Regression and PCA hold their weight in dimensionality reduction. While PCA can seem a little confusing when discussing eigenvalue and orthogonal projections, data scientists and machine learning engineers use both these techniques daily.

In short – use PCA when you have variables that all contribute equally to the variance within your data or your data has high amounts of multicollinearity. Use Lasso Regression whenever variables can be eliminated, and your dataset has already been cleansed of multicollinearity. 


Pros And Cons of Lasso Regression


Pros:

  • Variable selection: Lasso Regression automatically eliminates irrelevant or redundant variables, resulting in a more interpretable and less complex model.
  • Reduced overfitting: By applying a penalty to the coefficients, Lasso Regression helps prevent overfitting, leading to better generalization in the model.
  • Model simplicity: With fewer variables, Lasso Regression often results in more straightforward, more easily understood models.
  • Computationally efficient: Compared to other variable selection techniques, Lasso Regression can be more computationally efficient, making it suitable for large datasets.


Cons:

  • Inability to handle multicollinearity: Lasso Regression does not perform well with highly correlated variables, making it less suitable for datasets with multicollinearity.
  • Selection of only one variable in a group of correlated variables: Lasso Regression tends to select only one variable from a group of correlated variables, which might not always represent the underlying relationships best.
  • Bias in coefficient estimates: The L1 penalty used by Lasso Regression can introduce bias in the coefficient estimates, especially for small sample sizes or when the true coefficients are large.
  • Less stable than Ridge Regression: Lasso Regression can be more sensitive to small data changes than Ridge Regression, resulting in less stable estimates.


Pros And Cons of PCA


Pros:

  • Addresses multicollinearity: PCA effectively handles multicollinearity by transforming correlated variables into a new set of uncorrelated principal components.
  • Dimensionality reduction: PCA reduces data dimensions while retaining essential information, making it easier to analyze and visualize.
  • Improved model performance: By reducing noise and redundancy, PCA can lead to better model performance and more accurate predictions.
  • Computationally efficient: PCA can be an efficient technique for large datasets, as it reduces the complexity of the data without significant information loss.


Cons:

  • Loss of interpretability: PCA can result in a loss of interpretability, as the principal components may not have a clear or intuitive meaning compared to the original variables.
  • Sensitivity to scaling: PCA is sensitive to the scaling of variables, requiring careful preprocessing to ensure that the results are not influenced by the variables’ choice of units or magnitude.
  • Assumes linear relationships: PCA assumes linear relationships between variables and may not perform well with data that exhibits nonlinear relationships.
  • Information loss: Although PCA aims to retain as much information as possible, some information is inevitably lost during dimensionality reduction.
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What Is A Good Accuracy Score In Machine Learning? [Hard Truth] https://enjoymachinelearning.com/blog/what-is-a-good-accuracy-score-in-machine-learning/ https://enjoymachinelearning.com/blog/what-is-a-good-accuracy-score-in-machine-learning/#respond Thu, 22 Feb 2024 21:02:51 +0000 https://enjoymachinelearning.com/?p=2331 Read more

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A good accuracy score in machine learning depends highly on the problem at hand and the dataset being used.

High accuracy is achievable in some situations, while a seemingly modest score could be outstanding in others.

Many times, good accuracy is defined by the end goal of the machine learning algorithm. Is the algorithm good enough to achieve its initial goal?

If so, chasing higher accuracy may not even benefit you or your clients compared to chasing other things like ethical bias and improving infrastructure.


A Deeper Relationship With Accuracy Scoring

For instance, in the world of quantitative trading, or being a quant, a 51% accuracy rate over some extended period of time would lead to significant profits for you and your clients. 

This is because even a slight edge in predicting stock movements can translate into substantial gains over time. With enough capital behind you, you’d be the richest guy on Wall Street!

stock market

While chasing a higher accuracy score would obviously be beneficial here, even with a modest 51% accuracy, working on latency and infrastructure of your trading platform may end up being more fruitful and something that should be taken into account before spending money on trying to achieve a higher scoring metric.

While sometimes, as machine learning engineers, we quickly fall in love with the first score we see pop out from our algorithm, On your path to a good accuracy score, you should ensure that your modeling techniques are appropriate, logical, and well-tuned. 

Simply testing a few different approaches may not be enough to maximize the potential accuracy of your current business situation. 

This is why it’s important to thoroughly explore various techniques and fine-tune your model based on the specifics of your problem.

For example, if you’re using something like a gradient-boosted tree, hyperparameter tuning has proven time and time again to be beneficial to achieving a more accurate model.

Even after doing all of these things, it’s still sometimes hard to know if your model is any good and if you can be happy with your model’s performance.

Something that I do when working with a new machine learning algorithm and dataset is consult academic research and papers for relevant scoring metrics and benchmark scores.

This is highly beneficial and something that I’m constantly doing in my day-to-day work, since you will quickly know if your model’s performance is any good.

This will provide you with a baseline to gauge your model’s performance and help you identify areas for improvement. 

Additionally, it is essential to consider other performance metrics, such as precision, recall, F1-score, and area under the curve (AUC), as accuracy alone may not provide a comprehensive understanding of your model’s performance.

There is no one-size-fits-all answer to what constitutes a good accuracy score in machine learning. The appropriate score depends on the problem, dataset, and context.

By thoroughly researching and fine-tuning your modeling techniques and considering other performance metrics, you can work towards achieving the best possible outcome for your specific use case.


Other Articles In Our Accuracy Series:

Accuracy is used EVERYWHERE, which is fine because we wrote these articles below to help you understand it

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How To Choose The Right Algorithm For Machine Learning [Expert Guide] https://enjoymachinelearning.com/blog/how-to-choose-the-right-algorithm-for-machine-learning/ https://enjoymachinelearning.com/blog/how-to-choose-the-right-algorithm-for-machine-learning/#respond Thu, 22 Feb 2024 20:35:39 +0000 https://enjoymachinelearning.com/?p=2220 Read more

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I’ll be honest; choosing the right algorithm for machine learning can be one of the most challenging parts of our jobs.

Don’t worry; we’re here to help.

In this article, we’ll be breaking down the process of selecting the perfect algorithm for your project in a simple but effective easy-to-understand way.

We’ll start by taking a high-level look at the world of machine learning algorithms and what to consider before you even touch that keyboard. 

Then, we’ll review critical considerations and KPIs to help you know you’ve made the right choice.

By the end of this article, you’ll have a solid understanding of what to look for when choosing a machine learning algorithm and feel confident in your ability to make the best choice for your project.

If you want a future in this field, this is a MUST-READ.

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The Two Main Pillars of Machine Learning

Regarding machine learning, there are two main pillars:

Unsupervised learning and Supervised learning. Understanding these two distinct pillars is critical in choosing the right algorithm for your project.

Unsupervised learning is a type of machine learning where the algorithm is trained on a dataset without any specific target variable.

The algorithm must then find patterns and relationships within the data on its own.

This approach is used when you don’t have a target variable or are interested in clusters and groups within your data that aren’t extremely obvious.

For example, an unsupervised approach is excellent when looking for marketing groups and segments within a customer base to increase sales.

Conversely, supervised learning is a type of machine learning where the algorithm is trained on a labeled dataset with a particular target variable. 

This means the algorithm knows what it’s trying to both predict and improve on, allowing our algorithm a path to convergence.

Supervised learning is often preferred over unsupervised learning simply due to the information gain.

information gain


Let’s run through an example.

Say you have four columns of data and a “target variable.” Since our unsupervised algorithm does not use this target variable, it will take advantage of the four columns.

On the inverse, our supervised algorithm will have four columns of data plus the target variable. 

This means our supervised algorithm will have nearly 25% more data to work with!

It’s important to note that your dataset and problem usually dictate which machine learning pillar you should use. 

Remember, it’s best to utilize supervised algorithms whenever possible, as they provide more information and can help you achieve better results.

In summary, the two main pillars of machine learning are unsupervised and supervised learning.

While unsupervised learning helps uncover hidden patterns in data, supervised learning is preferred because it can converge on a target variable and provide the underlying algorithms with more information.


One Pillar Has Two Categories; The Other Has None

Under the umbrella of supervised learning, there are two main categories: regression and classification.

Regression is a type of supervised learning where the target variable is continuous, meaning it can take on any value within a range (Note, that range can be 0 to infinity)

The algorithm is trained to predict the target variable’s value based on the input variables’ values.

For example, using historical data on housing prices and their respective features, a regression algorithm can predict the price of a future house based on its features.

lil house on lil hand


On the other hand, classification is a type of supervised learning where the target variable is categorical, meaning it can only take on a limited number of values or categories. 

The algorithm is trained to predict the target variable’s category based on the input variables’ values. 

For example, one of the most classical machine learning problems is when using data on flower species and their respective features; a classification algorithm can predict the species of a flower based on its features.

It’s worth noting that these two categories only exist in supervised learning, as we have a target variable to learn from and optimize for.

This allows us to predict future values or groups based on the information we’ve learned from the target variable.

In unsupervised learning, we don’t have a target variable to tell us if we’re doing a good job with our predictions.

Our algorithms have nothing to optimize for; they only find patterns and relationships within the data.

This means unsupervised learning differs from supervised learning, requiring an almost different philosophical approach to choosing an algorithm.


What To Do Before You Start Coding Your Algorithm

Before you start coding your machine learning algorithm, sit down and ensure you understand your business problem and are being realistic with your data.

This will help you choose the correct algorithm for your project and ensure you get the best possible results.

When it comes to understanding your business problem, it’s essential to determine whether you’re trying to optimize toward a target (supervised learning) or looking for a new way to look at your data (unsupervised learning). 

For example, if you’re trying to predict future sales or which group a new member would belong to, you’ll need a target variable, and supervised learning would be the best approach.

On the other hand, unsupervised learning would be the better option if you’re looking to build up groups and clusters without guiding the algorithm.

Be realistic with your data. 

Supervised algorithms are immediately not an option if you don’t have a target variable. 

Nope

In this case, unsupervised learning is the only option available.

In summary, before you start coding your machine learning algorithm, understand your business problem and be realistic with your data.

Use your data as a guiding light, and make sure you choose the right approach based on your specific needs and the information available.


Quick Guide To Choosing The Right Machine Learning Algorithm

Here’s a quick mental map that I use to choose the right algorithm.


Understand your business problem: 
What are you trying to solve?

Understanding your business problem is the first step in choosing the right algorithm.

Before exploring different algorithms, you need to understand what you’re trying to achieve.


Explore your data:
 What columns and data do you have that’s usable?

You need to have a good understanding of the data you have available to you.

This will help you choose an algorithm that is well-suited to your specific needs and can take advantage of the data you have.


Determine if it’s a supervised or unsupervised problem:
 Once you have explored your data, you need to figure out if you’re dealing with a supervised or unsupervised problem.

This will help you narrow your options and choose the right approach for your problem.


Determine if it’s regression or classification:
 If it’s a supervised problem, you need to figure out if it’s regression or classification.

Are you predicting a continuous value or putting things into predetermined categories?


Find a group of algorithms to test:
 Use what you now know about your problem to find a group of algorithms within your group (such as supervised regression or unsupervised NLP problems).

This will help you narrow your options and find the right algorithm for your needs.

Note: As you’ve noticed, we say to find the group independently, as we have yet to recommend any specific data science algorithms. 

Finding the right machine-learning model is an iterative process.

Anyone suggesting “regression trees are best when doing X” does not understand machine learning and how algorithms work.


Assess each algorithm in the group:
 Test each algorithm in the group and assess its performance.

This will help you determine which algorithm performed the best and is the best choice for your specific problem.

Select the machine learning algorithm: Based on your results, select the machine learning algorithm that best suits your business problem.

This will be the algorithm you use to solve your problem and achieve your goals.

goals


What To Watch Out For When Choosing Your Algorithm

When choosing a machine learning algorithm, there are several things to remember when picking out that perfect algorithm.


First, don’t fall in love with an approach before it’s tested. 

Even if a particular algorithm looks good on paper or has worked well for others, it may not work the same for you.

It’s important to test multiple algorithms and compare their results to find the best one for your business needs.


Second, remember that your data and problem choose the algorithm, not you. 

You may have a favorite algorithm you’re excited to use, but it’s not the right choice if it doesn’t fit your data and problem well. 

Make sure to choose an algorithm that is well-suited to accomplish your goals!


Third, be aware that all algorithms seem good before they’re tested. 

Only after testing will you know how well an algorithm will perform on your problem. 

Don’t be swayed by an algorithm’s hype or popularity- test it and compare its results to other algorithms.


Fourth, don’t assume that a higher accuracy means a better algorithm. 

While accuracy is important, it’s not the only factor to consider.

Other factors such as speed, interpretability, and scalability also play a role in determining the best algorithm for your needs.


Fifth, ensure your data source is “tapped,” meaning you can’t get any more data. 

If you can obtain additional data, you can improve the performance of your algorithm or choose an altogether different algorithm that could perform much better (remember our unsupervised vs. supervised talk above).


Finally, remember that sometimes the best answer is the most straightforward answer. 

Don’t get caught up in using complex algorithms just to use a complex algorithm.

The simplest solution is often the best, especially if it provides the desired results with a lower risk of overfitting or over-complication.


How To Know You’ve Picked you’ve chosen the right learning model for your problem.

Ultimately, the best way to know if you’ve picked the right machine learning algorithm for your problem is if you’ve successfully solved the problem you initially set out to solve.

If your algorithm provides the desired results and you can achieve your goals, you’ve likely made the right choice.

On the other hand, if your algorithm is not providing the results you need, it’s time to go back and reassess.

It’s important to remember that machine learning algorithms are not one-size-fits-all solutions.

What works well for one problem may not work well for another.

This is why it’s important to test multiple algorithms and choose the best fit for your needs.

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