ONE-WAY BETWEEN-SUBJECTS DESIGN

Abstract

COMBINING TWO INDEPENDENT VARIABLES FACTORIALLY NAMING THE DESIGN In Chapter 6, we discussed a between-subjects design that contained a single independent variable (preparation time for the SAT). However, we are not limited to studying the effects of just one independent variable in a research design. In this chapter, we will deal with the inclusion of a second independent variable (note that we still have only one dependent variable). A design containing more than one independent variable is known as a factorial design when the variables are combined in a manner described in Section 8.1.2. When those independent variables are between-subjects variables, the design is called a between-subjects design or a between-subjects factorial design . Designs containing two between-subjects independent variables that are simultaneously varied are two-way between-subjects (factorial) designs . These designs are also sometimes referred to as two-way completely randomized designs because subjects are assumed to be randomly assigned to the various treatments. COMBINING INDEPENDENT VARIABLES IN A SINGLE DESIGN Intertwining two independent variables within the same design is done by combining them in a factorial fashion in which each level of one independent variable is combined with each level of the other independent variable. If our independent variables were, for example, gender (female and male) and size of city in which participants resided (large and small), then one combination of the levels of the independent variables might be females living in large cities. This would then be one condition or group in the factorial design.