Psychology 3780F/G Lecture Notes - Lecture 5: Random Assignment, Observational Error, Sertraline
15 Mar 2018
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Depends on: how groups are formed, how levels of independent variables are applied. Extent to which cause/effect explanation is warranted w/in an experiment. Extent to which study minimizes systematic error (bias) Three criteria: temporal precedence cause precedes effect, cause and effect are related, no alternate/spurious causes for effect confounding variables. Participants randomly assigned to groups: each participant must have an equal chance of being assigned to each group, random # generator, coin toss. Better still: participants randomly selected and then randomly assigned to groups. Equates groups on individual differences (removes one source of systematic bias) If groups differ on some pre-existing characteristic, then differences in dv might be due to that characteristic: invalidates conclusions. Independent variable (iv) specifically manipulated in context of experiment: manipulated to determine whether manipulation causes an effect. Dependent variable (dv) specifically measured in experiment. Extraneous variables: individual differences, experimental sessions. Qualitative variation (type: zoloft, prozac, paxil.
