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: www.rasch.org/rmt/rmt74m.htm

 

Size Limitations on Specifications and Data

Component

Maximum number

Limit

Notes

Responses in file

2,147,438,646

tested to 250,000,000

D

Data=

Ordinal response categories

in a rating scale

255

F

Models= or Rating scale=, per rating scale

Facets

255

tested to 60

F

Facets=

Elements

Element numbers must be in range

0 - 2,147,438,646

Maximum number of elements

across all facets is 4,000,000

D

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

Element label length

32,000

F

Labels=

Element groups

32,766

F

Labels=, per facet

Model statements

32,767

F

Models=

Rating scales

or other ordinal response scales

32,767

F

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

Bias terms

2,147,438,646

D

Models=, per model statement

Table arrangements

255

F

Arrange=

Element measure range

16 logits

P

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 http://en.wikipedia.org/wiki/Single-precision_floating-point_format and http://en.wikipedia.org/wiki/Double-precision_floating-point_format

 

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: www.winsteps.com Author: John Michael Linacre.
 

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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
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
Jan. 22-24, 2018, Mon-Wed. In-person workshop: Rasch Measurement for Everybody en español (A. Tristan, Winsteps), San Luis Potosi, Mexico. www.ieia.com.mx
April 10-12, 2018, Tues.-Thurs. Rasch Conference: IOMW, New York, NY, www.iomw.org
April 13-17, 2018, Fri.-Tues. AERA, New York, NY, www.aera.net
May 22 - 24, 2018, Tues.-Thur. EALTA 2018 pre-conference workshop (Introduction to Rasch measurement using WINSTEPS and FACETS, Thomas Eckes & Frank Weiss-Motz), https://ealta2018.testdaf.de
May 25 - June 22, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com
June 27 - 29, 2018, Wed.-Fri. Measurement at the Crossroads: History, philosophy and sociology of measurement, Paris, France., https://measurement2018.sciencesconf.org
June 29 - July 27, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com
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" www.promsociety.org
Aug. 10 - Sept. 7, 2018, Fri.-Fri. On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets), www.statistics.com
Sept. 3 - 6, 2018, Mon.-Thurs. IMEKO World Congress, Belfast, Northern Ireland www.imeko2018.org
Oct. 12 - Nov. 9, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com

 

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