PSYC 2250 Lecture Notes - Lecture 9: Random Assignment, Causal Inference, Quasi
16 Dec 2017
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Unit 9 (second half of chapter 11) (cid:0) Differences between true experiment (te) and quasi-experiment (qe) It is used to examine the effect of so-called. Independent variable on a dependent variable but causal inference is much more difficult: qe lacks random assignment of participants to condition while te allows. In other words, qe involves the selection of participants from existing group. Te randomly assign participants to condition while qe randomly select participants (cid:0) for different research conditions from groups that already exist. 2 pre-existing groups: day students vs correspondence students. If qe: not sure any differences resulted from the teaching methods or already pre-existed between groups. If te: any potential confounds from pre-existed groups would be equally considered thru random assignment to groups and so eliminated. Note: be sure to carefully consider pre-existing group differences as interpreting the results of any qe design. Has more external validity > te because it"s usually conducted in real environment or conditions.
