ERIC Number: EJ829915
Record Type: Journal
Publication Date: 2009
Abstractor: As Provided
Reference Count: 21
The Reliability of Difference Scores in Populations and Samples
Zimmerman, Donald W.
Journal of Educational Measurement, v46 n1 p19-42 Spr 2009
This study was an investigation of the relation between the reliability of difference scores, considered as a parameter characterizing a population of examinees, and the reliability estimates obtained from random samples from the population. The parameters in familiar equations for the reliability of difference scores were redefined in such a way that determinants of reliability in both populations and samples become more transparent. Computer simulation was used to find sample values and to plot frequency distributions of various correlations and variance ratios relevant to the reliability of differences. The shape of frequency distributions resulting from the simulations and the means and standard deviations of these distributions reveal the extent to which reliability estimates based on sample data can be expected to meaningfully represent population reliability.
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Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Authoring Institution: N/A