Book Image

Essential Statistics for Non-STEM Data Analysts

By : Rongpeng Li
Book Image

Essential Statistics for Non-STEM Data Analysts

By: Rongpeng Li

Overview of this book

Statistics remain the backbone of modern analysis tasks, helping you to interpret the results produced by data science pipelines. This book is a detailed guide covering the math and various statistical methods required for undertaking data science tasks. The book starts by showing you how to preprocess data and inspect distributions and correlations from a statistical perspective. You’ll then get to grips with the fundamentals of statistical analysis and apply its concepts to real-world datasets. As you advance, you’ll find out how statistical concepts emerge from different stages of data science pipelines, understand the summary of datasets in the language of statistics, and use it to build a solid foundation for robust data products such as explanatory models and predictive models. Once you’ve uncovered the working mechanism of data science algorithms, you’ll cover essential concepts for efficient data collection, cleaning, mining, visualization, and analysis. Finally, you’ll implement statistical methods in key machine learning tasks such as classification, regression, tree-based methods, and ensemble learning. By the end of this Essential Statistics for Non-STEM Data Analysts book, you’ll have learned how to build and present a self-contained, statistics-backed data product to meet your business goals.
Table of Contents (19 chapters)
1
Section 1: Getting Started with Statistics for Data Science
5
Section 2: Essentials of Statistical Analysis
10
Section 3: Statistics for Machine Learning
15
Section 4: Appendix

Exploring random forests with scikit-learn

Now that we're near the end of this chapter, I would like to briefly discuss random forests. Random forests are not strictly ensemble algorithms because they are an extension of tree methods. However, unlike bagging decision trees, they are different in an important way.

In Chapter 10, Statistical Techniques for Tree-Based Methods, we discussed how splitting the nodes in a decision tree is a greedy approach. The greedy approach doesn't always yield the best possible tree and it's easy to overfit without proper penalization. The random forest algorithm does not only bootstrap the samples, but also the features. Let's take our stroke risk dataset as an example. The heavy weight is the optimal feature to split on, but this rules out 80% of all possible trees, along with the other features of the root node. The random forest algorithm, at every splitting decision point, samples a subset of the features and picks the best...