SOAN 2120 Lecture Notes - Lecture 10: Random Assignment, Internal Validity, Experiment
4 Dec 2015
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The soloman four group design- represents elements of both posttest group only and pretest posttest control group design. First two had a pretest and two groups got a treatment and other two did not get the treatment. Compare o2 to o4 and o5 and o6 to see if it worked. If o4 different than o3 problem with internal validity. Non experimental research design do not have random assignment can match them if they have similar characteristics. If no r"s in front of it is non-equivalent control group design aka field experiment. If you wanted to see if a new teaching technique is effective it is hard to split up the kids. If you are a policy maker to see if minimum wage is effective you cannot randomly assign people to live in different cities. And any differences at end could be different not cause of treatment but difference beforehand.
