PSYC 2250 Lecture Notes - Lecture 10: Bar Chart, Experiment, Categorical Variable
1 Feb 2018
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Researchers can combine two or more ivs in the same experiment: called a factorial design . Used when: two or more ivs are qualitative, categorical data, dv is quantitative i. e. measured on a scale. Simplest kind of factorial design: 2 x 2 (two-by-two, 2 ivs each with 2 levels, creates 2 x 2 = 4 cells , text example: body type and food choices. Iv-a confederate food selection: 30 candies vs 2 candies. Iv-b confederate body type: thin vs obese, dv: participant"s candy consumption. 2 x 2 factorial design: main effects are determined from marginal means , independent a x b interaction determined from the 4-inner cells: If either pair is different, there is an interaction: note, this is a simple mains effects analysis, differences are examined at each level of the iv. Factorial designs with both manipulated and non-manipulated ivs. Called iv x pv designs: one iv is manipulated, other iv is participant variable, pv, e. g. , sex, age, etc.
