PSYC 201W Lecture Notes - Lecture 11: Random Assignment, Internal Validity, Quasi
2 Oct 2018
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Document Summary
Researcher choosing variables of the individuals compared to the participants choosing. X is used to indicate the treatment. Order of x and o indicates how they are occurring over time (what the order of treatment and observation) designs without a control group. Dv measured before and after treatment for one group. O(1) o(2) o(3) x o(4) o(5) o(6) Dv repeatedly measured at periodic intervals before and after treatment. If you see a big change after dv is observed than it did change. Design with a non equivalent control group. Sometimes not possible to randomly assign participants. Selection emerged as a major threat to internal validity. Selection x history (people in one group experience an outside event that the others did not) Selection x testing (cid:894)one group has testing effects and the other one doesn"t(cid:895) Selection x regression (more extreme scores for one group) Selection x attrition (rate of attrition differs between the group- rate of drop out)
