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

Underfitting, overfitting, and cross-validation

What is cross-validation and why is it needed? To talk about cross-validation, we must formally introduce two other important concepts first: underfitting and overfitting.

In order to obtain a good model for either a regression problem or a classification problem, we must fit the model with the data. The fitting process is usually referred to as training. In the training process, the model captures characteristics of the data, establishes numerical rules, and applies formulas or expressions.

Note

The training process is used to establish a mapping between the data and the output (classification, regression) we want. For example, when a baby learns how to distinguish an apple and a lemon, they may learn how to associate the colors of those fruits with the taste. Therefore, they will make the right decision to grab a sweet red apple rather than a sour yellow lemon.

Everything we have discussed so far is about the training technique...