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1Research and Evaluation Methodology, School of Human Development and Organizational Studies in Education, University of Florida, 1215 Norman Hall, Gainesville, FL 32611, USA. ahuggins@coe.ufl.edu
Journal of Applied Measurement
|December 14, 2012
Summary
Proportional weighting in test linking effect sizes like REMSD and RMSD(x) may hide differences in small subpopulations. This research explores weighting methods for accurate linking invariance testing.
Area of Science:
- Psychometrics
- Educational Measurement
- Statistical Modeling
Background:
- Test linking functions are crucial for equating scores across different test forms.
- Existing methods like REMSD and RMSD(x) are sensitive to subpopulation differences.
- Appropriate weighting is unclear with heterogeneous subpopulation sizes.
Purpose of the Study:
- To apply two distinct weighting methods to REMSD and RMSD(x) functions.
- To test for population invariance in test linking across disparate subpopulations.
- To compare the outcomes of differentially weighted effect sizes.
Main Methods:
- Application of proportional and alternative weighting schemes to REMSD and RMSD(x).
- Analysis of linking invariance across subpopulations with varying sample sizes.
- Comparative analysis of effect size indices under different weighting conditions.
Main Results:
- Proportional weights in REMSD and RMSD(x) can underestimate linking function differences.
- Small subpopulations are particularly susceptible to underestimation of differences.
- Differential weighting impacts the detection of linking invariance.
Conclusions:
- The choice of weighting method significantly affects the assessment of linking invariance.
- Proportional weighting may not be suitable for heterogeneous subpopulations in test linking.
- Further research is needed to optimize weighting strategies for robust test equating.
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