What Good are Statistics that Don't Generalize? ISSA!?

This question is the title of a paper by David Williamson Shaffer and Ronald C. Serlin in Educational Researcher, 2004, 33:9, 14-23. Their answer is: "Use ISSA!"

"ISSA [Intra-sample Statistical Analysis], then, extends the concept of verbal analysis to encompass qualitative data of any kind, including observations as well as interviews, task analyses as well as think-aloud protocols, video and field notes as well as audio transcripts. More importantly, ISSA provides a theoretical justification for the use of statistical analyses to support qualitative inference - and thus an occasion to reexamine the assumptions of quantitative and qualitative research traditions themselves." (p. 16).

ISSA parallels Rasch in its aim of progressing from observed manifest qualities, to abstract generalized quantities, to inferred latent qualities. Indeed, perhaps Rasch is an instance of ISSA.

But, as William Fisher remarks:

"Though I applaud its overall purpose and tone, it is too bad the authors, reviewers, and editors responsible for the Shaffer & Serlin (2004) article in the December Educational Researcher did not connect the qualitative data pattern shown in their Figure 1 with measurement theory. I find myself in a permanently perplexed state as a result of this near-constant hammering of the general unawareness that scaling and calibration inherently involve qualitative pattern-finding and pattern-imposing. Statisticians in general and the ones in this article seem unable to see past their descriptive orientation."

Here is Shaffer and Serlin's Figure 1: "A hypothetical subset of data on answers to post test questions shows how patterns observed can be obscured in an analysis of aggregated data" (p. 19).

These data would immediately support two standard Rasch analyses: (a) measures for persons and items when "related to personal experience", and (b) when "not related". Cross-plots of the person measures would reveal who is impacted, and cross-plots of the item difficulties would reveal what is impacted. But Shaffer and Serlin do not attempt Rasch analysis of their data, instead their focus is on weakening, rather than strengthening, the axiomatic basis of the numbers they produce.

What Good are Statistics that Don't Generalize? ISSA!? Fisher W.P. Jr. … Rasch Measurement Transactions, 2005, 18:4 p. 9

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Rasch Measurement Transactions & Rasch Measurement research papers - free	An Introduction to the Rasch Model with Examples in R (eRm, etc.), Debelak, Strobl, Zeigenfuse	Rasch Measurement Theory Analysis in R, Wind, Hua	Applying the Rasch Model in Social Sciences Using R, Lamprianou	El modelo métrico de Rasch: Fundamentación, implementación e interpretación de la medida en ciencias sociales (Spanish Edition), Manuel González-Montesinos M.
Rasch Models: Foundations, Recent Developments, and Applications, Fischer & Molenaar	Probabilistic Models for Some Intelligence and Attainment Tests, Georg Rasch	Rasch Models for Measurement, David Andrich	Constructing Measures, Mark Wilson	Best Test Design - free, Wright & Stone Rating Scale Analysis - free, Wright & Masters
Virtual Standard Setting: Setting Cut Scores, Charalambos Kollias	Diseño de Mejores Pruebas - free, Spanish Best Test Design	A Course in Rasch Measurement Theory, Andrich, Marais	Rasch Models in Health, Christensen, Kreiner, Mesba	Multivariate and Mixture Distribution Rasch Models, von Davier, Carstensen
Rasch Books and Publications: Winsteps and Facets
Applying the Rasch Model (Winsteps, Facets) 4th Ed., Bond, Yan, Heene	Advances in Rasch Analyses in the Human Sciences (Winsteps, Facets) 1st Ed., Boone, Staver	Advances in Applications of Rasch Measurement in Science Education, X. Liu & W. J. Boone	Rasch Analysis in the Human Sciences (Winsteps) Boone, Staver, Yale	Appliquer le modèle de Rasch: Défis et pistes de solution (Winsteps) E. Dionne, S. Béland
Introduction to Many-Facet Rasch Measurement (Facets), Thomas Eckes	Rasch Models for Solving Measurement Problems (Facets), George Engelhard, Jr. & Jue Wang	Statistical Analyses for Language Testers (Facets), Rita Green	Invariant Measurement with Raters and Rating Scales: Rasch Models for Rater-Mediated Assessments (Facets), George Engelhard, Jr. & Stefanie Wind	Aplicação do Modelo de Rasch (Português), de Bond, Trevor G., Fox, Christine M
Exploring Rating Scale Functioning for Survey Research (R, Facets), Stefanie Wind	Rasch Measurement: Applications, Khine	Winsteps Tutorials - free Facets Tutorials - free	Many-Facet Rasch Measurement (Facets) - free, J.M. Linacre	Fairness, Justice and Language Assessment (Winsteps, Facets), McNamara, Knoch, Fan

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