Steps Leading to a Straight Line: Constructing a Variable

Steps Leading to a Straight Line: Constructing a Variable

Social science involves the study of variables and the aspects, attributes, events, and behaviors that compose it. In social science, we move from ideas and observations to counts, measures, and predictions. The main idea, event, activity, behavior, or dimension on which we focus our observations we call our "variable."

A variable "varies" - the main idea stays the same, but its range of attributes can be arranged along a single line. There can be more of it or less of it. It can be weaker or stronger, smaller or larger, sicker or healthier, pro-something or anti-something. We study a variable because we want to measure its range and study the effects of other events on that range.

1. Can you describe your variable in just a few words, e.g., "patient progress after a certain treatment," or "people's attitudes toward politics?"

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2. What theory or ideas underlie your research interest and your selection of a variable?

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3. Think about what a "low performer" would be on your variable scale. Describe the kind of person, events, behaviors, etc., which would be at the beginning, or lowest end of your variable scale.

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4. Describe a "high performer," a person, event, set of behaviors, etc., that would be at the highest end of your variable.

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5. This is the hardest. Describe persons, events, etc. that would be in the middle range of your variable scale.

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6. Here (or on a separate sheet) write three items exemplifying the high, middle, and low range of your variable. (You may already have survey items from your ongoing research.) Number each item.

High end items (hard to agree with)

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Middle range items

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Low end items (easy to agree with)

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7. Below is a horizontal line representing your variable. Mark the end points in a way appropriate to your variable, e.g., less - more, easy - hard, sick - healthy. Arrange your items (by their numbers) along this variable line where you think they belong. (In other words, how do you think respondents will react to your items?) If you have trouble figuring out where an item belongs on the line, consider whether it is actually targeted on your variable.


You now have the framework for building an instrument with a linear array of hierarchical survey items that will elucidate your variable.

Marci Enos' Handout for Ben Wright's Questionnaire Design class, U. Chicago, 2000

Steps Leading to a Straight Line: Constructing a Variable. Enos M. … Rasch Measurement Transactions, 2008, 22:1 p. 1155




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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
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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
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Many-Facet Rasch Measurement (Facets) - free, J.M. Linacre Fairness, Justice and Language Assessment (Winsteps, Facets), McNamara, Knoch, Fan

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