July 2009

While the validity of any exam is really the accurate or valid interpretation of exam scores, such interpretations depend upon the content and constructs measured in the exam.  The appropriate knowledge and skill must be tested to achieve valid scores.

Tara McNaughton
Manager, Test Development and Analysis

Practice Analysis Issues and Methods
The primary purpose of certification exams is distinguishing individuals capable of practicing safely and effectively from those who can not.  It is essential to ensure that these high stakes examinations are valid, reliable, and objective measures of candidate ability.

A valid test is one that measures what it's meant to measure, with the underlying goal to accurately interpret scores.  In order to make valid interpretations of scores, examinations should have 1) face validity, 2) content validity and 3) construct validity. Face validity simply implies that the test appears to cover appropriate areas of practice.  Content and construct validity suggest that the test measures the knowledge and skills pertinent to the field of practice.  A strong argument for content validity can be achieved by conducting a practice analysis.

The test blueprint supports the construct and content validity and is the basis for selecting items to be included on an exam.  The blueprint of the exam should mirror practice in the field not only in terms of the knowledge and skill sampled, but in the proportion, depth, and breadth of coverage.

The test blueprint can be created to the specification of current work in the field by means of a practice analysis.  The practice analysis solicits information from practicing professionals in the field concerning what they need to know, the tasks they perform, and the relative frequency or importance of each.  Multiple related tasks form a content area on the test blueprint.
In the development, data collection, and analysis of a practice analysis, the expertise of subject matter experts, practitioners, and psychometricians is required.  The subject matter experts often do the initial development of the survey by identifying the areas of knowledge and skill required to practice effectively.  Psychometricians can offer guidance in survey development.  Practitioners may be involved in the early stages of development through field tests or focus groups to further refine the survey.  Finally, a sample of practitioners is selected as the survey respondents.

The practice analysis can emphasize tasks and skills, as well as, the knowledge necessary to perform appropriately in the field.  The general format may be a list of tasks followed by likert scale responses designed to measure the frequency or importance of each for the professional in the field.  Another perspective on developing the practice analysis questionnaire is to focus on the knowledge, skills, and abilities needed for safe and effective practice within the field.  Developing this type of questionnaire focuses more on the personal attributes of the professional, as well as, the tasks being performed.

It can be difficult to encourage busy professionals to take the time to answer the survey.  Strategies to maximize response rates include limiting the length of the survey to a page or two which focus on the most critical issues.  Some organizations do follow ups such as multiple mailings, reminder phone calls and emails, or offering incentives for completing the survey.

The final step is the analysis of the data and the structuring of a usable test blueprint.  Psychometricians produce summary information concerning the measured importance and frequency of each item on the survey.  Subject matter experts review these results and make refinements in the final product based on their knowledge and experience in the field.

One interesting finding in the literature is that different approaches to practice analyses can produce very similar results.  The quality of expert judgments in developing and reviewing the analysis may influence the outcome more than the method or expense used for the practice analysis.  This underscores the importance of expert judgments in determining the eventual test blueprint that is developed.  While practitioners may be the best judges of frequency, some research indicates that measures of criticality may be best left to expert judgments.
Measurement Research Associates, Inc.
505 North Lake Shore Dr., Suite 1304
Chicago, IL  60611
Phone: (312) 822-9648     Fax: (312) 822-9650

Rasch-Related Resources: Rasch Measurement YouTube Channel
Rasch Measurement Transactions & Rasch Measurement research papers - free An Introduction to the Rasch Model with Examples in R (eRm, etc.), Debelak, Strobl, Zeigenfuse Rasch Measurement Theory Analysis in R, Wind, Hua Applying the Rasch Model in Social Sciences Using R, Lamprianou Journal of Applied Measurement
Rasch Models: Foundations, Recent Developments, and Applications, Fischer & Molenaar Probabilistic Models for Some Intelligence and Attainment Tests, Georg Rasch Rasch Models for Measurement, David Andrich Constructing Measures, Mark Wilson Best Test Design - free, Wright & Stone
Rating Scale Analysis - free, Wright & Masters
Virtual Standard Setting: Setting Cut Scores, Charalambos Kollias Diseño de Mejores Pruebas - free, Spanish Best Test Design A Course in Rasch Measurement Theory, Andrich, Marais Rasch Models in Health, Christensen, Kreiner, Mesba Multivariate and Mixture Distribution Rasch Models, von Davier, Carstensen
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Applying the Rasch Model (Winsteps, Facets) 4th Ed., Bond, Yan, Heene Advances in Rasch Analyses in the Human Sciences (Winsteps, Facets) 1st Ed., Boone, Staver Advances in Applications of Rasch Measurement in Science Education, X. Liu & W. J. Boone Rasch Analysis in the Human Sciences (Winsteps) Boone, Staver, Yale Appliquer le modèle de Rasch: Défis et pistes de solution (Winsteps) E. Dionne, S. Béland
Introduction to Many-Facet Rasch Measurement (Facets), Thomas Eckes Rasch Models for Solving Measurement Problems (Facets), George Engelhard, Jr. & Jue Wang Statistical Analyses for Language Testers (Facets), Rita Green Invariant Measurement with Raters and Rating Scales: Rasch Models for Rater-Mediated Assessments (Facets), George Engelhard, Jr. & Stefanie Wind Aplicação do Modelo de Rasch (Português), de Bond, Trevor G., Fox, Christine M
Exploring Rating Scale Functioning for Survey Research (R, Facets), Stefanie Wind Rasch Measurement: Applications, Khine Winsteps Tutorials - free
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Many-Facet Rasch Measurement (Facets) - free, J.M. Linacre Fairness, Justice and Language Assessment (Winsteps, Facets), McNamara, Knoch, Fan

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