Examining reliability and validity of job analysis survey data.

Historically, job analysis has played a fundamental role for developing and validating licensure and certification examinations. Still, research on what constitutes reliable and valid job analysis data is lacking. This paper illustrates several ways to examine the reliability and validity of job analysis survey results. Generalizability theory and the many-facets Rasch model are applied to investigate consistency and generalizability in task importance measures, to suggest reliable sample size, and to justify the number and use of rating scales. By using random samples from job analysis data for two professions with divergent job activities, this study finds that a representative sample as small as 400 respondents produces reliable estimates of task importance to the same degree of generalizability as obtained from a larger sample of job analysis respondents. Analyses of rating scales suggest that the effectiveness of using different numbers and types of rating scales depends on the nature of a profession.