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Poster

A Split Population Model for Middle-Category Inflation in Ordered Survey Responses Bagozzi, Benjamin Uploaded 08-01-2011 Keywords split-population models ordered dependent Variables survey data Europe public opinion Abstract Recent research find that, for social desirability reasons, uninformed individuals disproportionately give ``neither agree nor disagree'' type responses to survey attitude questions, even when a ``don't know'' option is available (Sturgis et al. 2010). Such ``face-saving don't knows'' inflate the indifference (i.e. middle) categories of ordered attitude variables with non-ordered responses. When this inflation occurs within one's dependent variable, estimates from ordered probit/logit models are biased and inefficient. This poster develops a set of mixture models (the middle-inflated ordered probit with and without correlated errors) that estimate and account for the presence of ``face-saving'' responses in middle-categories of ordered survey response variables, and applies these models to (1) simulated data and (2) a commonly studied survey question measuring support for EU-membership among EU-candidate countries. Findings suggest that, when middle-category inflation is present in one's ordered dependent variable, the estimates obtained from middle-category mixture models are less biased than---and in some cases substantively distinct from---the estimates obtained from ``naive'' ordered probit models.