MEASUREMENT RESEARCH ASSOCIATES TEST INSIGHTSFebruary 2010
 Greetings,   Examiner consistency within his/her own rating pattern in an oral examination should be monitored.  This brief study explores whether an examiner's internal consistency is related to his/her severity.  Lidia MartinezManager, Test Development and Analysis
The Relationship between Examiner Severity and Consistency
Examiner severity is the convenient term for the tendency of an examiner to give lower ratings or higher ratings. This tendency towards severity or leniency is due to examiner expectations, characteristics, and standards. A severity measure for each examiner in the many-facet Rasch analysis is calculated using all of the ratings the examiner gave during the course of the examination.

Examiner consistency is measured by a mean-square fit statistic. This statistic is based on the ratio of observed error variance to expected error variance.  It's expected value is 1 (i.e., a ratio of 1:1). The mean square fit statistic for an examiner indicates his/her consistency or how well his/her pattern of ratings meet expectations given examiner severity and candidate ability (i.e., fit to the model). Neither too high nor too low fit statistics are desirable.

When the examiner's fit statistic is less than .5, it indicates over 50% less variance in his/her ratings than is expected. It is likely that the examiner tended to give many candidates the same rating, regardless of their ability. This type of examiner is not only too predictable, but he/she is not distinguishing differences among candidates. When the fit statistic is greater than 1.5, it indicates over 50% more variance in his/her ratings than is expected. It is likely that the examiner gave candidates unexpectedly high or low ratings compared to their overall ability.

The question is whether there is a correlation between measured examiner severity and examiner consistency (outfit mean square fit statistic). To study this question, random performance examinations were selected and the Pearson correlation between severity and consistency for the examiners was calculated.

The table below shows that there are low, non-significant correlations between examiner severity and consistency.  The table also shows that the vast majority of the examiners meet the criteria for consistency.  The low correlations between severity and consistency show that 1) most examiners are internally consistent in their rating of candidates; 2) that examiners, regardless of their measured severity, tend to be consistent in their rating of candidates; and 3) that severity does not predict consistency or vice-versa.  The low numbers of inconsistent examiners reflects good examiner training and an understanding of the rating process.

 Exam N of Examiners Correlation between Severity and Consistency Significance(ns = not significant) Number  (%) of inconsistent examiners Exam 1 44 .05 ns 0 Exam 2 24 -.14 ns 0 Exam 3 72 .00 ns 4 (5%) Exam 4 146 -.09 ns 4 (3%) Exam 5 81 -.06 ns 2 (2%)

 Measurement Research Associates, Inc. 505 North Lake Shore Dr., Suite 1304 Chicago, IL  60611 Phone: (312) 822-9648     Fax: (312) 822-9650 www.MeasurementResearch.com

Rasch Publications
Rasch Measurement Transactions (free, online) Rasch Measurement research papers (free, online) Probabilistic Models for Some Intelligence and Attainment Tests, Georg Rasch Applying the Rasch Model 3rd. Ed., Bond & Fox Best Test Design, Wright & Stone
Rating Scale Analysis, Wright & Masters Introduction to Rasch Measurement, E. Smith & R. Smith Introduction to Many-Facet Rasch Measurement, Thomas Eckes Invariant Measurement: Using Rasch Models in the Social, Behavioral, and Health Sciences, George Engelhard, Jr. Statistical Analyses for Language Testers, Rita Green
Rasch Models: Foundations, Recent Developments, and Applications, Fischer & Molenaar Journal of Applied Measurement Rasch models for measurement, David Andrich Constructing Measures, Mark Wilson Rasch Analysis in the Human Sciences, Boone, Stave, Yale
in Spanish: Análisis de Rasch para todos, Agustín Tristán Mediciones, Posicionamientos y Diagnósticos Competitivos, Juan Ramón Oreja Rodríguez

 FORUM Rasch Measurement Forum to discuss any Rasch-related topic

Coming Rasch-related Events
June 30 - July 29, 2017, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com
July 31 - Aug. 3, 2017, Mon.-Thurs. Joint IMEKO TC1-TC7-TC13 Symposium 2017: Measurement Science challenges in Natural and Social Sciences, Rio de Janeiro, Brazil, imeko-tc7-rio.org.br
Aug. 7-9, 2017, Mon-Wed. In-person workshop and research coloquium: Effect size of family and school indexes in writing competence using TERCE data (C. Pardo, A. Atorressi, Winsteps), Bariloche Argentina. Carlos Pardo, Universidad Catòlica de Colombia
Aug. 7-9, 2017, Mon-Wed. PROMS 2017: Pacific Rim Objective Measurement Symposium, Sabah, Borneo, Malaysia, proms.promsociety.org/2017/
Aug. 10, 2017, Thurs. In-person Winsteps Training Workshop (M. Linacre, Winsteps), Sydney, Australia. www.winsteps.com/sydneyws.htm
Aug. 11 - Sept. 8, 2017, Fri.-Fri. On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets), www.statistics.com
Aug. 18-21, 2017, Fri.-Mon. IACAT 2017: International Association for Computerized Adaptive Testing, Niigata, Japan, iacat.org
Sept. 15-16, 2017, Fri.-Sat. IOMC 2017: International Outcome Measurement Conference, Chicago, jampress.org/iomc2017.htm
Oct. 13 - Nov. 10, 2017, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com
Jan. 5 - Feb. 2, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com
Jan. 10-16, 2018, Wed.-Tues. In-person workshop: Advanced Course in Rasch Measurement Theory and the application of RUMM2030, Perth, Australia (D. Andrich), Announcement
Jan. 17-19, 2018, Wed.-Fri. Rasch Conference: Seventh International Conference on Probabilistic Models for Measurement, Matilda Bay Club, Perth, Australia, Website
April 13-17, 2018, Fri.-Tues. AERA, New York, NY, www.aera.net
May 25 - June 22, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com
June 29 - July 27, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com
Aug. 10 - Sept. 7, 2018, Fri.-Fri. On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets), www.statistics.com
Oct. 12 - Nov. 9, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com