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Barnow, Burt S.; And Others – 1980
Selectivity bias arises in program evaluation when the treatment or control status of the subjects is related to unmeasured characteristics that themselves are related to the program outcome under study. This situation has the potential to lead to an incorrect estimation of the treatment effect when assignment to treatment and control groups is…
Descriptors: Control Groups, Evaluation Methods, Experimental Groups, Models
Edwards, Roger H.; Bridewell, Joy L. – 1979
Possible causes for the discrepancy between the ABT report on the national Project Follow Through and the Saint Louis, Missouri program were discussed: (1) ABT data were positively biased because of non-random, differential attrition from the program and control groups; (2) positive ABT data were due to use of a particular cohort group; or (3)…
Descriptors: Achievement Gains, Affective Objectives, Compensatory Education, Elementary Education