PSY 121 Chapter Notes - Chapter 10: Dependent And Independent Variables, Statistical Significance, Repeated Measures Design
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A design with only two levels of the independent variable cannot provide very much information about the exact form of the relationship between the independent and dependent variables. B/c there are only two levels, the relationship can be described only with a straight line. An experiment with only two levels cannot yield such exact information. If a curvilinear relationship is predicted, at least three levels must be used. Researchers frequently are interested in comparing more than two groups. Increasing the number of independent variables: factorial designs. Researchers often manipulate more than one independent variable in a single experiment. Typically, two or three independent variables are operating simultaneously. This type of experimental design is a closer approximation of real-world conditions, in which independent variables do not exist by themselves. Researchers recognize that in any given situation a number of variables are operating to affect behavior. Factorial designs are designs with more than one independent variable (or factor0.
