Graduation Year

2008

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Measurement and Evaluation

Major Professor

John M. Ferron, Ph.D.

Keywords

Standard setting, Angoff values, Rater reliability, Rater error, Simulation

Abstract

While each phase of the test development process is crucial to the validity of the examination, one phase tends to stand out among the others: the standard setting process. The standard setting process is a time-consuming and expensive endeavor. While it has received the most attention in the literature among any of the technical issues related to criterion-referenced measurement, little research attention has been given to generalizing the resulting performance standards. This procedure has the potential to improve the standard setting process by limiting the number of items rated and the number of individual rater decisions. The ability to generalize performance standards has profound implications both from a psychometric as well as a practicality standpoint. This study was conducted to evaluate the extent to which minimal competency estimates derived from a subset of multiple choice items using the Angoff standard setting method would generalize to the larger item set.

Individual item-level estimates of minimal competency were simulated from existing and simulated item difficulty distributions. The study was designed to examine the characteristics of item sets and the standard setting process that could impact the ability to generalize a single performance standard. The characteristics and the relationship between the two item sets included three factors: (a) the item difficulty distributions, (b) the location of the 'true' performance standard, (c) the number of items randomly drawn in the sample. The characteristics of the standard setting process included four factors: (d) number of raters, (e) percentage of unreliable raters, (f) magnitude of 'unreliability' in unreliable raters, and (g) the directional influence of group dynamics and discussion. The aggregated simulation results were evaluated in terms of the location (bias) and the variability (mean absolute deviation, root mean square error) in the estimates.

The simulation results suggest that the model of using partial item sets may have some merit as the resulting performance standard estimates may 'adequately' generalize to those set with larger item sets. The simulation results also suggest that elements such as the distribution of item difficulty parameters and the potential for directional group influence may also impact the ability to generalize performance standards and should be carefully considered.

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