Miskey Cues

Multiple-choice tests are straightforward to answer, straightforward to optically scan, and deceptively straightforward to analyze. As an analyst, it is easy to delude oneself that all is well, when, in fact, things have gone awry.

A frequent source of self-deception is the answer key or code book. All multiple-choice answer keys tend to look the same, just a string of letters or numbers: "ACDEBCDA". A garbled or misaligned key looks just as valid as a correct key. Even a key from a different test appears as good as the genuine key. It's extremely easy to perform an entire analysis and report the results without noticing there's been a major flaw in the process.

How can we avoid this kind of embarrassing misadventure? What must we watch for? Let's compare some results using correct and incorrect keys. The figures show the variable maps for two analyses of the same data. The first analysis uses the correct key. In the second analysis, every other item has the wrong key. What has happened?

MEASURE                  PERSONS     ITEMS
 4.0                            . +
 3.0                        .#### + P Q
 2.0                 .########### + R
 1.0                .############ + S T
  .0    .######################## + U
-1.0                 .########### + V W
-2.0                  .########## + X
-3.0                        .#### + Y Z
-4.0                           ## +

Analysis with correct key. Person and items spread out. Persons and items aligned.

MEASURE                  PERSONS  +  ITEMS
 4.0                              +
 3.0                              + Y
 2.0                              +
 1.0                          .## + P Q R U W
  .0                       .##### + S T
-1.0 .########################### +
-2.0                              + V
-3.0                      .###### + X
-4.0                          .## + Z

Analysis with incorrect key. Persons and items bunched up. Persons below items.

Impact on Items:
The intended item order was "P" to "Z". With the correct key, the items are ordered in that intended descending order of difficulty. With an incorrect key, the construct validity of the items collapses. The incorrect key still has half the items keyed correctly. Even so the item hierarchy is lost in a confusing jumble. Of course, to detect this problem, the analyst must be familiar enough with the items on the test to predict their order of difficulty. Statistics alone can not reveal item-content disorder. Statistics, however, do give warning signs: observe how the items in the figure bunch up.

Impact on Persons:
With a wrong key, getting an item correct becomes random. This causes examinees to bunch up in ability. In addition, their performance is somewhat below the mean apparent item difficulty because examinee responses are unlikely to match the incorrect key even 50% of the time.

The moral: Without construct validity, you have nothing. Don't leave home without it!

Miskey cues. Garcia HI. … Rasch Measurement Transactions, 1992, 5:4 p.185

Rasch Books and Publications
Invariant Measurement: Using Rasch Models in the Social, Behavioral, and Health Sciences, 2nd Edn. George Engelhard, Jr. & Jue Wang	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
Introduction to Many-Facet Rasch Measurement (Facets), Thomas Eckes	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	Appliquer le modèle de Rasch: Défis et pistes de solution (Winsteps) E. Dionne, S. Béland
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
Other Rasch-Related Resources: Rasch Measurement YouTube Channel
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

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