Chapter 14

Regression: Linear and Multiple


Summarizing a relationship

Working with regression

Hypothesis testing and regression

Balancing many relationships

One of the main things you do when you work with statistics is make predictions. The idea is to take data on one or more variables, and use these data to predict a 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. First, I show you how to analyze the relationship between one variable and another. Then I show you how to analyze the relationship between a variable and two others. These analyses involve a good bit of calculation, and Excel is more than equal to the task.

The Plot of Scatter

Sahutsket University is an exciting, dynamic institution. Every year, the school receives thousands of applications. One challenge the Admissions Office faces is this: Applicants want the Office to predict what their GPAs (grade-point averages on a 4.0 scale) will be if they attend Sahutsket.

What’s the best prediction? Without knowing anything about an applicant, and only knowing its own students’ GPAs, the answer is clear: It’s the average GPA at Sahutsket U. Regardless of who the applicant is, that’s all the Admissions Office can say if its knowledge ...

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