Statistical Analysis with R Essentials For Dummies

Chapter 12

Linear Regression

IN THIS CHAPTER

Summarizing a relationship

Working with regression

Linear regression in R

One of the main things you do when you work with statistics is make predictions. The idea is to use data from one or more variables to predict the value of another variable. To do this, you have to understand how to summarize relationships among variables, and to test hypotheses about those relationships.

In this chapter, I introduce regression, a statistical way to do just that. Regression also enables you to use the details of relationships to make predictions.

The Plot of Scatter

FarMisht Consulting, Inc., is a consulting firm with a wide range of specialties. It receives numerous applications from people interested in becoming FarMisht consultants. Accordingly, FarMisht Human Resources has to be able to predict which applicants will succeed and which ones will not. They’ve developed a Performance measure that they use to assess their current employees. The scale is 0–100, where 100 indicates top performance.

What’s the best prediction for a new applicant? Without knowing anything about an applicant, and knowing only their own employees’ Performance scores, ...