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PDF pending restorationCalkins, Dick S. – 1974
The mathematical derivation of the statistics used for inference in some linear models assumes that the values of the independent variables are measured without error. This assumption is often disregarded when these models are utilized in research. This study is an investigation of the consequences of the violation of this assumption for one…
Descriptors: Analysis of Covariance, Computer Programs, Error of Measurement, Error Patterns
Download full textOlejnik, Stephen F.; Algina, James – 1983
Parametric analysis of covariance was compared to analysis of covariance with data transformed using ranks. Using a computer simulation approach the two strategies were compared in terms of the proportion of Type I errors made and statistical power when the conditional distribution of errors were: (1) normal and homoscedastic, (2) normal and…
Descriptors: Analysis of Covariance, Control Groups, Data Collection, Error of Measurement
Bump, Wren M. – 1992
An analysis of covariance (ANCOVA) is done to correct for chance differences that occur when subjects are assigned randomly to treatment groups. When properly used, this correction results in adjustment of the group means for pre-existing differences caused by sampling error and reduction of the size of the error variance of the analysis. The…
Descriptors: Analysis of Covariance, Equations (Mathematics), Error of Measurement, Experimental Groups
Peer reviewedLevin, Joel R.; Subkoviak, Michael J. – Applied Psychological Measurement, 1977
Textbook calculations of statistical power or sample size follow from formulas that assume that the variables under consideration are measured without error. However, in the real world of behavioral research, errors of measurement cannot be neglected. The determination of sample size is discussed, and an example illustrates blocking strategy.…
Descriptors: Analysis of Covariance, Analysis of Variance, Error of Measurement, 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
Coffman, William E.; Shigemasu, Kazuo – 1978
Appraisal of a school's relative effectiveness is complicated by: (1) the need to control for input differences; (2) measurement error in input measures; and (3) small sample size within schools. This study compares the performance of two successive cohorts in 19 schools in a small midwestern city on the five Iowa Tests of Basic Skills using both…
Descriptors: Academic Achievement, Accountability, Achievement Gains, Analysis of Covariance
Olejnik, Stephen F.; Porter, Andrew C. – 1978
The statistical properties of two methods of estimating gain scores for groups in quasi-experiments are compared: (1) gains in scores standardized separately for each group; and (2) analysis of covariance with estimated true pretest scores. The fan spread hypothesis is assumed for groups but not necessarily assumed for members of the groups.…
Descriptors: Academic Achievement, Achievement Gains, Analysis of Covariance, Analysis of Variance
