title: When Middle Really Means "Top" or "Bottom": An Analysis of the 16PF5 Using Bock's Nominal Response Model.
abstract: When self-report items with a Likert-type scale include a middle response option (e.g., Unsure, Neither agree nor disagree, or ?), this middle option is assumed to measure a level of the trait intermediate between the high and low response categories. In this study, we tested this assumption in the 16 Personality Factor Questionnaire, Version 5 (16PF5) by fitting Bock's nominal response model in the U.S. and UK standardization samples of the 16PF5. We found that in many cases, the middle option was indicative of higher levels of the latent trait than the ostensibly highest response option. In certain other cases, it was indicative of lower levels of the latent trait than the ostensibly lowest response option. This undermines the use of a simple successive integer scoring scheme where responses in adjacent response categories are assigned scores of 0, 1, and 2. Recommendations for alternative scoring schemes are provided. Results also suggested that certain personality traits, especially neurotic traits, are associated with a tendency toward selecting the middle option.
authors.affiliation: a Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh , United Kingdom.|b Department of Psychology , University of Edinburgh , United Kingdom.
authors.forename: Aja Louise
authors.initials: AL
authors.lastname: Murray
authors.affiliation: b Department of Psychology , University of Edinburgh , United Kingdom.
authors.forename: Tom
authors.initials: T
authors.lastname: Booth
authors.affiliation: c Department of Psychology , University of Amsterdam , The Netherlands.
authors.forename: Dylan
authors.initials: D
authors.lastname: Molenaar
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D011594:Psychometrics / Q000379:methods*; D055815:Young Adult