A Comparison of Two Methods for Structuring Performance Domains

This research evaluated two methods for structuring a performance domain for a certification test in emergency nursing. The first method utilized task frequency ratings obtained from a national sample of 659 emergency nurses who completed a job analysis survey consisting of 125 tasks. The second method was based on judgments of task similarity among the same 125 tasks; the similarity judgments were provided by a panel of 21 subject-matter experts. The two types of data, task frequency ratings and task similarity judgments, were subjected to cluster analysis and multidimensional scaling in order to derive a framework for organizing the 125 tasks into some limited number of performance categories. The similarity judgments produced fewer clusters and fewer dimensions and were more adequately modeled by both multivariate procedures. The results based on the similarity judgments were also easier to interpret within a conceptually meaningful framework. The results question the traditional approach of applying multivariate procedures to task frequency ratings for purposes of clustering tasks and structuring performance domains.