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Adair, John G.; And Others – 1987
A meta-analysis was conducted on 44 educational studies that used either a (labelled) Hawthorne control group, a manipulation of Hawthorne effects, or a group designed to control for the Hawthorne effect. The sample included published journal articles, ERIC documents or unpublished papers, and dissertations. The studies were coded on 20 variables,…
Descriptors: Control Groups, Educational Research, Effect Size, Experimental Groups
Vermillion, James E. – 1980
The presence of artifactual bias in analysis of covariance (ANCOVA) and in matching nonequivalent control group (NECG) designs was empirically investigated. The data set was obtained from a study of the effects of a television program on children from three day care centers in Mexico in which the subjects had been randomly selected within centers.…
Descriptors: Analysis of Covariance, Control Groups, Error of Measurement, Experimental Groups
Tallmadge, G. Kasten – 1991
Problems with conducting randomized field experiments in education are explored. Focus is on problems encountered while evaluating a group of dropout prevention projects. Project planners were asked to manipulate the subject eligibility criteria until they identified as eligible three to four times as many students as they could serve. They were…
Descriptors: Attrition (Research Studies), Control Groups, Dropout Programs, Educational Experiments
