SVDFILE= singular-value decomposition file
Singular-value decomposition (SVD) is a technique for factoring a data matrix. Here it is used to look for patterns in the Rasch residuals which may indicate multidimensionality. SVD values are estimated by iterating through the residual data matrix. Each residual is explained, as much as possible, by a value attributed to the person (row) and a value attributed to the item (column). These values are multiplied.
SVDFILE=? opens a Browse window
The general form of the Rasch-SVD model is:
Xni = Eni + Vn*Ui ± ε
where Xni is the observation when person n meets item i. Eni is the Rasch-expected value. Vn is the SVD value for the person. Ui is the SVD value for the item. ε is the unexplained part of the residual.
After the first set of SVD values have been estimated, the process can be continued deeper down to further levels:
Xni = Eni + V1n*U1i + V2n*U2i ... ± ε
SVD control settings. These can be in the control file, or from the Output file menu, SVDFILE option.
is the number of SVD terms (factors) to be estimated for each residual. SVD computation can be concluded with Ctrl+F.
is the maximum number of epochs (iterations through the data) for estimating each SVD factor
is the minimum improvement of the root-mean-square residuals based on the current SVD estimates at the end of an SVD iteration (epoch) through the data matrix of residuals in order for SVD estimation to finish for that SVD factor.
is the type of residual to be decomposed. R = the raw residual or S = the standardized residual.
name of the output file for the SVD values.
SVD file format:
RMSR = Root-mean-square-residual corresponding to the column of Rasch measures or SVD factors.
RMSS = Root-mean-square-standardized-residual corresponding to the column of Rasch measures or SVD factors.
MEASURE = Rasch measure in Table 14 etc.
1 2 3 4 ... are the columns of SVD values. For each SVD factor, every person and every item has an SVD value.
SVD factors corresponding to extreme scores have 0 values.
Help for Winsteps Rasch Measurement Software: www.winsteps.com. Author: John Michael Linacre
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|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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