Book Image

Machine Learning for Imbalanced Data

By : Kumar Abhishek, Dr. Mounir Abdelaziz
Book Image

Machine Learning for Imbalanced Data

By: Kumar Abhishek, Dr. Mounir Abdelaziz

Overview of this book

As machine learning practitioners, we often encounter imbalanced datasets in which one class has considerably fewer instances than the other. Many machine learning algorithms assume an equilibrium between majority and minority classes, leading to suboptimal performance on imbalanced data. This comprehensive guide helps you address this class imbalance to significantly improve model performance. Machine Learning for Imbalanced Data begins by introducing you to the challenges posed by imbalanced datasets and the importance of addressing these issues. It then guides you through techniques that enhance the performance of classical machine learning models when using imbalanced data, including various sampling and cost-sensitive learning methods. As you progress, you’ll delve into similar and more advanced techniques for deep learning models, employing PyTorch as the primary framework. Throughout the book, hands-on examples will provide working and reproducible code that’ll demonstrate the practical implementation of each technique. By the end of this book, you’ll be adept at identifying and addressing class imbalances and confidently applying various techniques, including sampling, cost-sensitive techniques, and threshold adjustment, while using traditional machine learning or deep learning models.
Table of Contents (15 chapters)

Model performance comparison of various oversampling methods

Let’s examine how some popular models perform with the different oversampling techniques we’ve discussed. We’ll use two datasets for this comparison: one synthetic and one real-world dataset. We’ll evaluate the performance of four oversampling techniques, as well as no sampling, using logistic regression and random forest models.

You can find all the related code in this book’s GitHub repository. In Figure 2.15 and Figure 2.16, we can see the average precision score values for both models on the two datasets:

Figure 2.15 – Performance comparison of various oversampling techniques on a synthetic dataset

Figure 2.16 – Performance comparison of various oversampling techniques on the thyroid_sick dataset

Based on these plots, we can draw some useful conclusions:

  • Effectiveness of oversampling: In general, using...