CH 10

• Factor


  An independent variable
• Factors


  • Sleeping pills
  • Alcohol
• Factors


  • Independent and do not interact
• Factors interact


  The effect of one drug changes at different levels of the other drug
• Factorial design


  Contains more than one independent variable
• Factorial design


  • Effect of psychotherapy (IV1) and antidepressant drugs (IV2) on depression (DV)
• Main effect


  The action of a single IV on the DV
• There can be as many main effects as independent variables
• Main effect


  • Exercise intensity or duration separately reducing depression
• Interaction


  The joint effect of two or more IVs on the DV
• Interaction


  • Antidepressant Paxil producing greater reductions in depression in the Cognitive Behavior Therapy (CBT) condition than the Waiting List condition
• Higher-order interaction


  An interaction among three or more IVs
• Higher-order interaction


  • Perpetrator's gender, relationship to the child, and severity of abuse jointly determining sentence length
• For three independent variables, there are AB, AC, BC, and ABC interactions
• Factor-labeling method


  Lists the two factors in parentheses after the numerical notation
• Factor and levels method


  Lists the two factors and their respective levels after the numerical notation
• Advantage of factor and levels method

  Provides more detailed information about the design than the factor-labeling method
• Factorial design


  • More efficient as it combines several one-factor experiments and allows studying interactions
  • Can achieve greater external validity as it can better recreate the complexity of the multivariate environment
• Between-subjects designs


  • Should be kept simple due to practical limitations like number of subjects, time, and interpretability of results