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| Porter, Andrew C. | 3 |
| McSweeney, Maryellen | 1 |
| Olejnik, Stephen F. | 1 |
| Pravalpruk, Kowit | 1 |
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Download full textPravalpruk, Kowit; Porter, Andrew C. – 1974
When random assignment has been accomplished and an analysis of covariance (ANCOVA) is being used to correct for initial differences among treatment groups, use of unreliable covariables not only decreases the power of ANCOVA, but also causes ANCOVA to test biased treatment effects. Several correction procedures have been suggested for the single…
Descriptors: Analysis of Covariance, Mathematical Models, Research Problems, Statistical Analysis
Porter, Andrew C.; McSweeney, Maryellen – 1974
A Monte Carlo technique was used to investigate the small sample goodness of fit and statistical power of several nonparametric tests and their parametric analogues when applied to data which violate parametric assumptions. The motivation was to facilitate choice among three designs, simple random assignment with and without a concomitant variable…
Descriptors: Analysis of Covariance, Analysis of Variance, Comparative Analysis, Goodness of Fit
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
