Chapter 11: Multiple Group Experiments


I. Overview

II. Advantages of using more than two values of the independent variable

A. Comparing more than two kinds of treatments

B. Comparing more than two levels (amounts) of an independent variable to increase external validity

C. Using multiple levels to improve construct validity of experiments

III. Analysis of multiple group experiments

A. An intuitive overview

B. A closer look at the analysis of a multiple group experiment

1. Assessing within group variability

2. Assessing between group variability

3. Comparing variances

a. Using an F table

b. Calculating degrees of freedom

4. The meaning of statistical significance

5. Pinpointing a significant effect

a. Post-hoc t tests among group means

b. Post-hoc trend analysis

IV. Concluding remarks

Summary

Key terms

Exercises


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