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ERIC Number: ED523588
Record Type: Non-Journal
Publication Date: 2011-Sep
Pages: 98
Abstractor: ERIC
Reference Count: 32
Variability in Pretest-Posttest Correlation Coefficients by Student Achievement Level. NCEE 2011-4033
Cole, Russell; Haimson, Joshua; Perez-Johnson, Irma; May, Henry
National Center for Education Evaluation and Regional Assistance
State assessments are increasingly used as outcome measures for education evaluations. The scaling of state assessments produces variability in measurement error, with the conditional standard error of measurement increasing as average student ability moves toward the tails of the achievement distribution. This report examines the variability in pretest-posttest correlation coefficients of state assessment data for samples of low-performing, average-performing, and proficient students to illustrate how sample characteristics (including the measurement error of observed scores) affect pretest-posttest correlation coefficients. As an application, this report highlights how statistical power can be attenuated when correlation coefficients vary according to sample characteristics. Population achievement data from four states and two large districts in both English/Language Arts and Mathematics for three recent years are examined. The results confirm that pretest-posttest correlation coefficients are smaller for samples of low performers, reducing statistical power for impact studies. We also find substantial variation across state assessments. These findings suggest that it may be useful to assess the pretest-posttest correlation coefficients of state assessments for an intervention's target population during the planning phase of a study. Population descriptive statistics for ELA and Mathematics assessments for all eligible students in available years are appended. (Contains 26 tables, 8 figures and 23 footnotes.)
National Center for Education Evaluation and Regional Assistance. Available from: ED Pubs. P.O. Box 1398, Jessup, MD 20794-1398. Tel: 877-433-7827; Web site:
Publication Type: Reports - Research
Education Level: Elementary Secondary Education
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: National Center for Education Evaluation and Regional Assistance (ED)
IES Funded: Yes