ABSTRACT
In chapter 4 we introduced two different types of independent variables, active and attribute. We also described how an independent variable has different values, which we called levels. In addition, we described the dependent variable as the outcome measure or criterion of the study. How participants become assigned to the levels of the independent variable, in part, determines the type of quantitative research approach, which was the topic of chapter 5. In chapter 6 we introduced the concept of internal validity, and how it should be used to judge the merits of a study. It is worth going back to chapter 5 and reviewing Fig. 5.1 to examine the relationship between type of independent variable and type of quantitative research approach. The randomized experimental and quasi-experimental approaches have an active independent variable, whereas the comparative and associational approaches have an attribute independent variable.
