Chapter 12 cell: A condition in an experiment; in a simple experiment, it can represent the level of one independent variable; in a factorial design it represents one of the possible combinations of two independent variables. factorial design: A study in which there are two or more independent variables, or factors. interaction effect: A result from a factorial design, in which the difference in the levels of one independent variable changes, depending on the level of the other independent variable; a difference in differences. Also called interaction. main effect: In a factorial design, the overall effect of one independent variable on the dependent variable, averaging over the levels of the other independent variable. marginal means: In a factorial design, the arithmetic means for each level of an independent variable, averaging over the levels of another independent variable. participant variable: A variable such as age, gender, or ethnicity whose levels are selected (i.e., measured), not manipulated. Chapter 13 Quasi-experiment: A study that is similar to an experiment except that the researchers do not have full experimental control (e.g., they may not be able to randomly assign participants to the independent variable conditions). 4 Types Independent Groups: nonequivalent control group design: An independent-groups quasi-experiment that has at least one treatment group and one comparison group, but participants have not been randomly assigned to the two groups. nonequivalent control group pretest/posttest design : An independent-groups quasi-experiment that has at least one treatment group and one comparison group, in which participants have not been randomly assigned to the two groups, and in which at least one pretest and one posttest are administered.
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- Fall '08