Confirming Test Structure and Measurement Characteristics

Does an instrument maintain its measurement characteristics in a new situation? A particular medical condition can interact with test items at three intensity levels:
(i) to introduce minor perturbations in the observations, with no practical import;
(ii) to provide diagnostically useful misfit, but without degrading the validity of the overall measures,
(iii) to fracture the instrument into two or more subsets of items producing incompatible measures.
When an instrument is designed to produce measures of more than one attribute, interactions with medical conditions may obscure the distinctions between the measures.

The Chicago Multiscale Depression Inventory (CMDI; Nyenhuis et al., in press) is designed to produce three distinct measures for three aspects of depression: Mood (9 items), Evaluative symptoms (6 items) and Vegetative symptoms (9 items). Items are one word or a brief phrase that describe a symptom of depression. Data were collected from 433 multiple sclerosis patients. Patients rated how they felt during the last week on a 5-point scale, from 1 ("Not at all") to 5 ("Extremely"). All items were combined into one Rasch analysis, followed by a principal component analysis of the standardized residuals. Items identified as loading on the first factor (or component) in the residuals were excluded from subsequent factors. The utility of the instrument for MS patients would be supported if the factor structure reflected the instrument's intended functioning.

Figure 1 shows that the first factor in the residuals contrasts the 9 Vegetative items against the others. After removal of the Vegetative items from the analysis, the first factor contrasts, in Figure 2, the Evaluative against the Mood items. The item difficulty hierarchies can be examined to confirm the stability of the construct definitions.

The practical implications of these three factors can be investigated by constructing 3 measures for each patient, one for each subset of items. The Figures opposite show the relationships between the three sets of person measures. They are correlated across patients, confirming that they converge to measure "depression" when it is useful to regard all items as measuring one variable. The relationship between Evaluative and Mood symptoms (bottom Figure) is strongest, reflecting their clear distinction from Vegetative symptoms in Figure 1. Overall, the structure of the CMDI has been confirmed for these patients.

Chih-Hung Chang
Evanston Northwestern Healthcare

Nyenhuis, D. L., Luchetta, T., Yamamoto, C., Terrien, A., Bernardin, L., Rao, S. M., & Garron (in press). The development, standardization and initial validation of the Chicago Multiscale Depression Inventory. Journal of Personality Assessment.

Chung C.-H. (1998) Confirming Test Structure and Measurement Characteristics. Rasch Measurement Transactions 12:1 p. 622-3.

Confirming Test Structure and Measurement Characteristics. Chung C.-H. … Rasch Measurement Transactions, 1998, 12:1 p. 622-3.

Please help with Standard Dataset 4: Andrich Rating Scale Model

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

To be emailed about new material on
please enter your email address here:

I want to Subscribe: & click below
I want to Unsubscribe: & click below

Please set your SPAM filter to accept emails from welcomes your comments:

Your email address (if you want us to reply):


ForumRasch Measurement Forum to discuss any Rasch-related topic

Go to Top of Page
Go to index of all Rasch Measurement Transactions
AERA members: Join the Rasch Measurement SIG and receive the printed version of RMT
Some back issues of RMT are available as bound volumes
Subscribe to Journal of Applied Measurement

Go to Institute for Objective Measurement Home Page. The Rasch Measurement SIG (AERA) thanks the Institute for Objective Measurement for inviting the publication of Rasch Measurement Transactions on the Institute's website,

Coming Rasch-related Events
April 26-30, 2017, Wed.-Sun. NCME, San Antonio, TX, - April 29: Ben Wright book
April 27 - May 1, 2017, Thur.-Mon. AERA, San Antonio, TX,
April 29, 2017, Sat., 16:35 to 18:05. NCME Presidents Invitational Symposium: a new book commemorating Ben Wright's life and career, 16:35 to 18:05, San Antonio, TX,
May 26 - June 23, 2017, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps),
June 30 - July 29, 2017, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps),
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,
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,
Aug. 10, 2017, Thurs. In-person Winsteps Training Workshop (M. Linacre, Winsteps), Sydney, Australia.
Aug. 11 - Sept. 8, 2017, Fri.-Fri. On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets),
Aug. 18-21, 2017, Fri.-Mon. IACAT 2017: International Association for Computerized Adaptive Testing, Niigata, Japan,
Sept. 15-16, 2017, Fri.-Sat. IOMC 2017: International Outcome Measurement Conference, Chicago,
Oct. 13 - Nov. 10, 2017, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps),
Jan. 5 - Feb. 2, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps),
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
May 25 - June 22, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps),
June 29 - July 27, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps),
Aug. 10 - Sept. 7, 2018, Fri.-Fri. On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets),
Oct. 12 - Nov. 9, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps),
The HTML to add "Coming Rasch-related Events" to your webpage is:
<script type="text/javascript" src=""></script>


The URL of this page is