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ERIC Number: ED531247
Record Type: Non-Journal
Publication Date: 2012
Pages: 12
Abstractor: ERIC
Reference Count: 31
Time-Indexed Effect Size for P-12 Reading and Math Program Evaluation
Lee, Jaekyung; Finn, Jeremy; Liu, Xiaoyan
Society for Research on Educational Effectiveness
This study contextualizes an effect-size-like index of educational treatment effects or any group mean differences in academic achievement by referencing time. The new effect size metric can enrich effect size interpretations while serving as a supplement (but not substitute) for conventional standardized effect size measures. Specifically, the authors introduce a new time-indexed effect size metric (d') based on the notion of time-varying academic growth trajectories in P-12 reading and math as evidenced through empirical analyses of U.S. national longitudinal datasets. They take an approach to the validation of this new index by employing (1) interpretive arguments (i.e., specification of proposed interpretations and uses of the index) and (2) validity arguments (i.e., evaluation of the interpretive arguments based on evidence) (see Kane, 2006). First, they provide a framework for calculations and interpretations of a time-indexed effect size based on two different designs of educational research/evaluation: pretest-posttest or repeated measures designs and posttest only designs. Second, they present methodological steps for developing longitudinal norms of growth and converting d into d'. Third, as one element of the supporting validity evidence, they demonstrate how to interpret and use d' through applications of the time-indexed effect size metric to well-known research examples. The results of d and d' for the same studies are compared and cross-validated. Last, they discuss threats to validity, caveats, and ameliorative strategies for valid interpretations and uses of the time-indexed effect size. (Contains 3 tables, 2 figures and 1 footnote.)
Society for Research on Educational Effectiveness. 2040 Sheridan Road, Evanston, IL 60208. Tel: 202-495-0920; Fax: 202-640-4401; e-mail:; Web site:
Publication Type: Reports - Evaluative
Education Level: Elementary Secondary Education
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: Society for Research on Educational Effectiveness (SREE)
Identifiers - Assessments and Surveys: Early Childhood Longitudinal Survey