scholarly journals Estimating the Political Center from Aggregate Data: An Item Response Theory Alternative to the Stimson Dyad Ratios Algorithm

2014 ◽  
Vol 22 (1) ◽  
pp. 115-129 ◽  
Author(s):  
Anthony J. McGann
Keyword(s):  
Item Response Theory ◽  
Item Response ◽  
Median Voter ◽  
Theory Model ◽  
Free Software ◽  
Model Fit ◽  
The Political ◽  
Response Theory ◽  
The United Kingdom ◽  
Political Center

This article provides an algorithm to produce a time-series estimate of the political center (or median voter) from aggregate survey data, even when the same questions are not asked in most years. This is compared to the existing Stimson dyad ratios approach, which has been applied to various questions in political science. Unlike the dyad ratios approach, the model developed here is derived from an explicit model of individual behavior—the widely used item response theory model. I compare the results of both techniques using the data on public opinion from the United Kingdom from 1947 to 2005 from Bartle, Dellepiane-Avellaneda, and Stimson. Measures of overall model fit are provided, as well as techniques for testing model's assumptions and the fit of individual items. Full code is provided for estimation with free software WinBUGS and JAGS.

scholarly journals A Multidimensional Item Response Theory Model for Continuous and Graded Responses With Error in Persons and Items

2021 ◽  
pp. 001316442199841
Author(s):  
Pere J. Ferrando ◽  
David Navarro-González
Keyword(s):  
Item Response Theory ◽  
Item Response ◽  
Theory Model ◽  
Response Model ◽  
Response Theory ◽  
Continuous Response ◽  
Graded Responses ◽  
Graded Response ◽  
Continuous Responses ◽  
Differential Measurement Error

Item response theory “dual” models (DMs) in which both items and individuals are viewed as sources of differential measurement error so far have been proposed only for unidimensional measures. This article proposes two multidimensional extensions of existing DMs: the M-DTCRM (dual Thurstonian continuous response model), intended for (approximately) continuous responses, and the M-DTGRM (dual Thurstonian graded response model), intended for ordered-categorical responses (including binary). A rationale for the extension to the multiple-content-dimensions case, which is based on the concept of the multidimensional location index, is first proposed and discussed. Then, the models are described using both the factor-analytic and the item response theory parameterizations. Procedures for (a) calibrating the items, (b) scoring individuals, (c) assessing model appropriateness, and (d) assessing measurement precision are finally discussed. The simulation results suggest that the proposal is quite feasible, and an illustrative example based on personality data is also provided. The proposals are submitted to be of particular interest for the case of multidimensional questionnaires in which the number of items per scale would not be enough for arriving at stable estimates if the existing unidimensional DMs were fitted on a separate-scale basis.

On the Validity of Forced Choice Scores Derived From the Thurstonian Item Response Theory Model

Assessment ◽  
2019 ◽  
Vol 27 (4) ◽  
pp. 706-718 ◽  
Author(s):  
Kate E. Walton ◽  
Lina Cherkasova ◽  
Richard D. Roberts
Keyword(s):  
Item Response Theory ◽  
Item Response ◽  
Discriminant Validity ◽  
Criterion Validity ◽  
Theory Model ◽  
Forced Choice ◽  
Response Theory ◽  
Test Criterion ◽  
Convergent And Discriminant Validity ◽  
Response Biases

Forced choice (FC) measures may be a desirable alternative to single stimulus (SS) Likert items, which are easier to fake and can have associated response biases. However, classical methods of scoring FC measures lead to ipsative data, which have a number of psychometric problems. A Thurstonian item response theory (TIRT) model has been introduced as a way to overcome these issues, but few empirical validity studies have been conducted to ensure its effectiveness. This was the goal of the current three studies, which used FC measures of domains from popular personality frameworks including the Big Five and HEXACO, and both statement and adjective item stems. We computed TIRT and ipsative scores and compared their validity estimates. Convergent and discriminant validity of the scores were evaluated by correlating them with SS scores, and test-criterion validity evidence was evaluated by examining their relationships with meaningful outcomes. In all three studies, there was evidence for the convergent and test-criterion validity of the TIRT scores, though at times this was on par with the validity of the ipsative scores. The discriminant validity of the TIRT scores was problematic and was often worse than the ipsative scores.

Evaluation of the Multiple Sclerosis Walking Scale-12 (MSWS-12) in a Dutch sample: Application of item response theory

2016 ◽  
Vol 22 (14) ◽  
pp. 1867-1873 ◽  
Author(s):  
Lidwine Brigitta Mokkink ◽  
Francisca Galindo-Garre ◽  
Bernard MJ Uitdehaag
Keyword(s):  
Multiple Sclerosis ◽  
Item Response Theory ◽  
Item Response ◽  
Theory Model ◽  
Walking Ability ◽  
Response Theory ◽  
Trait Level ◽  
Sample Application ◽  
Dutch Sample

Background: The Multiple Sclerosis Walking Scale-12 (MSWS-12) measures walking ability from the patients’ perspective. We examined the quality of the MSWS-12 using an item response theory model, the graded response model (GRM). Methods: A total of 625 unique Dutch multiple sclerosis (MS) patients were included. After testing for unidimensionality, monotonicity, and absence of local dependence, a GRM was fit and item characteristics were assessed. Differential item functioning (DIF) for the variables gender, age, duration of MS, type of MS and severity of MS, reliability, total test information, and standard error of the trait level (θ) were investigated. Results: Confirmatory factor analysis showed a unidimensional structure of the 12 items of the scale, explaining 88% of the variance. Item 2 did not fit into the GRM model. Reliability was 0.93. Items 8 and 9 (of the 11 and 12 item version respectively) showed DIF on the variable severity, based on the Expanded Disability Status Scale (EDSS). However, the EDSS is strongly related to the content of both items. Conclusion: Our results confirm the good quality of the MSWS-12. The trait level (θ) scores and item parameters of both the 12- and 11-item versions were highly comparable, although we do not suggest to change the content of the MSWS-12.

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