Date of Degree
PhD (Doctor of Philosophy)
Psychological and Quantitative Foundations
Robbins, Steven B
First Committee Member
Second Committee Member
Third Committee Member
Schmidt, Frank L
The main purpose of this study was to determine if validity coefficients for ACT scores, both composite scores and subject area test scores, and high school grade point average (HSGPA) decayed or held stable over eight semesters of undergraduate study in science, technology, engineering, and mathematics (STEM) fields at civilian four-year institutions, and whether the decay patterns differed from those found in non-STEM fields at the same institutions. Data from 62,212 students at 26 four-year institutions were analyzed in a hierarchical meta-analysis in which student major category (SMC), gender, and admission selectivity levels were considered potential moderators. Four sets of analyses were run. The first was by the three SMCs: STEM-Quantitative majors, STEM-Biological majors, and non-STEM majors. The second was SMC by gender. The third was SMC by admission selectivity level. The fourth was SMC by gender by admission selectivity level.
The results across all four analyses indicated that ACT score validity coefficients for STEM-Quantitative and STEM-Biological majors decayed less over eight semesters than the validity coefficients for non-STEM majors did. This was true for the uncorrected and corrected validity coefficients. For the HSGPA validity coefficients, this was true for the corrected validity coefficients. Non-STEM majors had very similar validity decay patterns regardless of the level of analysis. However, four of the eight STEM subgroups in the final set of analyses had minimal amounts of decay, and in some instances small amounts of validity growth.
ACT, decay, meta-analysis, stability, STEM, validity
xx, 313 pages
Includes bibliographical references (pages 97-104).
Copyright 2012 Paul Westrick
Westrick, Paul Andrew. "Validity decay versus validity stability in stem and non-stem fields." PhD (Doctor of Philosophy) thesis, University of Iowa, 2012.