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Raffeld, Paul; Reynolds, William M. – 1977
The pretest-posttest design referred to as Design 2 by Campbell and Stanley (1963) is commonly used in educational research and evaluation. The tenability of the assumption of a zero population difference commonly used with this design is questioned. A nonzero population estimate based on the mean difference observed in test-retest reliability…
Descriptors: Control Groups, Correlation, Experimental Groups, Hypothesis Testing
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