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

Growing and pruning a classification tree

Let's start by examining the dataset one more time. We will first simplify our problem to a binary case so that the demonstration of decision tree growing is simpler. Let's examine Figure 10.1 again.

For the purpose of this demonstration, I will just group the middle-risk and high-risk patients into the high-risk group. This way, the classification problem becomes a binary classification problem, which is easier to explain. After going through this section, you can try the exercises on the original three-category problem for practice.

The following code snippet generates the new dataset that groups middle-risk and high-risk patients together:

df["stroke_risk"] = df["stroke_risk"].apply(lambda x: "low" if x == "low" else "high")

The new dataset will then look as follows:

Figure 10.3 – Binary stroke risk data

Now, let's think about the...