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psychometrikavol. 81, no. 1, 135160 March 2016doi: 10.1007/s11336-014-9434-9
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Web End = ITEM RESPONSE MODELS FOR FORCED-CHOICE QUESTIONNAIRES: A COMMON FRAMEWORK
Anna Brown
UNIVERSITY OF KENT
In forced-choice questionnaires, respondents have to make choices between two or more items presented at the same time. Several IRT models have been developed to link respondent choices to underlying psychological attributes, including the recent MUPP (Stark et al. in Appl Psychol Meas 29:184203, 2005) and Thurstonian IRT (Brown and Maydeu-Olivares in Educ Psychol Meas 71:460502, 2011) models. In the present article, a common framework is proposed that describes forced-choice models along three axes:(1) the forced-choice format used; (2) the measurement model for the relationships between items and psychological attributes they measure; and (3) the decision model for choice behavior. Using the framework, fundamental properties of forced-choice measurement of individual differences are considered. It is shown that the scale origin for the attributes is generally identied in questionnaires using either unidimensional or multidimensional comparisons. Both dominance and ideal point models can be used to provide accurate forced-choice measurement; and the rules governing accurate person score estimation with these models are remarkably similar.
Key words: forced choice, ipsative data, Thurstonian choice model, unfolding model, BradleyTerry model, dominance model, ideal point model.
The most popular way of gathering responses to personality and similar items is to ask respondents to evaluate one item at a time, independently of other items (single-stimulus format). An alternative way is to ask respondents to choose between several items presented at the same time, for example to indicate which statement describes them bestI am relaxed most of the time or I do things according to a plan. Regardless of whether all or none of the items is evaluated favorably by a respondent, he/she will be forced to make a choice (hence the name forced-choice format). With the single-stimulus formats, respondents make absolute judgments about every item. With the forced-choice formats, respondents engage in comparative judgments, assessing relative merits of the items.
Comparative judgments may be preferred to absolute judgments in many contexts. Because it is impossible to endorse all items, comparative judgments are effective whenever differentiation between responses is desired. For example, in situations where...