Assessing Validity in Multiple Regression Studies

The preceding five chapters explain how to use multiple regression to analyze the

relationship among variables in a data set. In this chapter, we step back and

ask, What makes a study that uses multiple regression reliable or unreliable?

We focus on statistical studies that have the objective of estimating the causal effect of

a change in some independent variable, such as class size, on a dependent variable,

such as test scores. For such studies, when will multiple regression provide

a useful estimate of the causal effect, and, just as importantly,

when will it fail to do so? To answer these questions, this chapter presents