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Lix, Lisa M.; Keselman, H. J. – Educational and Psychological Measurement, 1998
Comparison of six procedures to test for location equality among two or more groups when population variances are heterogeneous suggests that, when the variance homogeneity and normality assumptions are not satisfied, and the design is unbalanced, the use of any of these test statistics with the usual least squares estimators is not recommended.…
Descriptors: Comparative Analysis, Estimation (Mathematics), Least Squares Statistics, Research Design
Peer reviewed Peer reviewed
Yarnold, Paul R. – Educational and Psychological Measurement, 1996
This article addresses the characterization and circumvention of E. H. Simpson's paradox in designs involving two ordered variables and illustrates the recommended procedure using a two-sample application involving estimation of correlation and a single-subject application involving the estimation of lag(1) autocorrelation. (Author/SLD)
Descriptors: Classification, Correlation, Estimation (Mathematics), Research Design
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Hopkins, Kenneth D.; Chappell, David – Educational and Psychological Measurement, 1994
Quick power estimates for detecting a difference in two population proportions are expedient during early stages of research planning. Such estimates are tabled and graphed in this article. They are shown to be conservative but accurate for most research situations when proportions fall in the range of 0.25 to 0.75. (SLD)
Descriptors: Comparative Analysis, Data Collection, Estimation (Mathematics), Graphs
Peer reviewed Peer reviewed
Marcoulides, George A.; Goldstein, Zvi – Educational and Psychological Measurement, 1990
A methodology for determining the optimal number of observations to use in a measurement design when resource constraints are imposed is presented. Two- and three-facet designs are outlined. Parallel closed form formulae can easily be determined for other designs. (TJH)
Descriptors: Equations (Mathematics), Estimation (Mathematics), Generalizability Theory, Mathematical Models