Initial estimates are obtained by the PROX algorithm, and then more refined ones by the JMLE (UCON) algorithm (or by the Facets implementation of PMLE). Check that convergence is occurring by reviewing the "Residual" and "Change" columns for smaller values each iteration. The iterative process can be terminated by pressing Ctrl+S simultaneously.
With T3onscreen= No, so that detailed output is displayed:
PROX - "normal approximation algorithm" is used to make initial estimates.
If "PROX Recount required" is displayed, some elements or categories had a 0 or perfect score. Measure for these can not be estimated directly, so their estimation is deferred and all marginal scores recounted without them. PROX ceases when the maximum change is less than 0.1 logits
JMLE= "joint maximum likelihood estimation" makes more precise estimates. The least-converged elements or rating-scale categories are shown (largest residual, largest residual percent, largest logit change). We want max.= to approach 0.
more JMLE iterations
JMLE ceases when the max.= values are small, and the convergence criteria are met. If the maximum residual does not decrease noticeably per iteration, then Estimation menu, "Bigger".. If the maximum residual oscillates between large positive and negative values, then Estimation menu "Reduce". See also "My analysis does not converge."
Column headings have the following meanings:
Facet = Name of the facet, as given in specifications or "Scale:" if details apply to a category of a rating scale (or partial credit).
Name = Name of element within Facet or model statement of a rating scale (or partial credit)
No./Cat = Number of element within facet or category number of a rating scale (or partial credit)
Raw = Raw score (= sum of categories, after renumbering if necessary), or count of responses in category, an integer
Expected = Score or count expected based on current estimates, in tenths
Residual = Difference between observed Score and Expected score, in tenths
Resd% = Residual/(Maximum score - minimum score)%.
Value = Revised estimate of parameter in log-odds units (logits) as a result of this iteration.
Change = Change in logit estimate from logit estimate of the previous iteration.
max.= is the maximum change or residual corresponding to any element, used to determine convergence.
Iteration = The number of times PROX or JMLE has been applied to the data.
Analysis fails after recounting
Table 3. Iteration Report
| Iteration Max. Score Residual Max. Logit Change |
| Elements % Categories Elements Steps |
Validating subset connection... (Subsets=No to bypass)
| PROX 1 Recount required 3.6889 |
Consolidating 2 subsets
Subset connection O.K.
| PROX 2 Recount required 2.3615 |
| PROX 3 Recount required 3.6142 |
| PROX 20 Recount required -20.4497 |
| PROX 21 Recount required -5.2877 |
Error F36: All data eliminated as extreme.
This report suggests that Models= does not match the data or that there are not enough observations to estimate the rating-scale structure.
Suggestion: specify a predefined rating-scale structure, such as Binomial Trials. For instance:
Models = ?, ?, B6 ; instead of R6
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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|
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|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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