Maximum size limitations on specifications and data

The Facets software program will operate with a minimum of 1 facet, 1 element and two observations per element. For statistically stable measures to be estimated, 30 observations per element are needed:


Size Limitations on Specifications and Data


Maximum number



Responses in file


tested to 250,000,000



Ordinal response categories

in a rating scale



Models= or Rating scale=, per rating scale



tested to 60




Element numbers must be in range

0 - 2,147,438,646

Maximum number of elements

across all facets is 4,000,000


Labels=, numbered up to 2,147,483,646

Element label length




Element groups



Labels=, per facet

Model statements




Rating scales

or other ordinal response scales



Models=  or Rating scale=, includes scales generated by models with "#"

Bias terms



Models=, per model statement

Table arrangements




Element measure range

16 logits


Estimation can go higher, useful up to 44 logits range

D = limited by available disk and memory space

F = Fixed upper limit

P = limited by arithmetic precision.


Most Facets computations are at the level of single-precision floating point arithmetic (32-bits). Some crucial computations are at the level of double-precision floating point (64-bits). See and


For a  few computations which can exceed the integer-precision capabilities of double-precision floating point, "currency" computations are used (which are those used for exact computations of huge sums of money.)

Help for Facets Rasch Measurement Software: Author: John Michael Linacre.

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Facets Rasch measurement software. Buy for $149. & site licenses. Freeware student/evaluation download
Winsteps Rasch measurement software. Buy for $149. & site licenses. Freeware student/evaluation download

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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 with Raters and Rating Scales: Rasch Models for Rater-Mediated Assessments, George Engelhard, Jr. & Stefanie Wind 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
Winsteps Tutorials Facets Tutorials Rasch Discussion Groups


Coming Rasch-related Events
April 10-12, 2018, Tues.-Thurs. Rasch Conference: IOMW, New York, NY,
April 13-17, 2018, Fri.-Tues. AERA, New York, NY,
May 22 - 24, 2018, Tues.-Thur. EALTA 2018 pre-conference workshop (Introduction to Rasch measurement using WINSTEPS and FACETS, Thomas Eckes & Frank Weiss-Motz),
May 25 - June 22, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps),
June 27 - 29, 2018, Wed.-Fri. Measurement at the Crossroads: History, philosophy and sociology of measurement, Paris, France.,
June 29 - July 27, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps),
July 25 - July 27, 2018, Wed.-Fri. Pacific-Rim Objective Measurement Symposium (PROMS), (Preconference workshops July 23-24, 2018) Fudan University, Shanghai, China "Applying Rasch Measurement in Language Assessment and across the Human Sciences"
Aug. 10 - Sept. 7, 2018, Fri.-Fri. On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets),
Sept. 3 - 6, 2018, Mon.-Thurs. IMEKO World Congress, Belfast, Northern Ireland
Oct. 12 - Nov. 9, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps),


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