PSYC 201W Lecture 6: Chapter 7 Control Techniques in Experimental Research
2 Sep 2015
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Random selection rarely used researchers focus on the independent variable. Assume the researcher already has a sample and our focus will be on control techniques. Goal of experimentation: identify the causal effect of the independent variable (iv) on the dependent variable (dv) Must have internal validity to do this: requires control of extraneous variables, eliminate differential influence confounds. Random assignment (strong, cheap, before the experiment; not guarantee each grou ps are equal, but in long run the average will be similar; larger the group, better : a control technique to equate groups of participants. Matching variables: extraneous variable used in matching: use of any of a variety of techniques to equate participants in the treatment groups on specific variables. Should be done with variables thought to be related to the iv or may confound. E. g. , intelligence, age, gender: advantages of matching. Controls for the variables on which participants are matched. Example: gender and conformity study using only females.
