Investigating method effects associated with the wording direction of items of the Social Physique Anxiety Scale

Abstract

Purpose: The use of psychometric instruments to measure latent concepts is common. The development of these instruments usually involves mechanisms to reduce response bias, such as the inclusion of reversed items. The aim of this study was to investigate method effects related to the wording direction of the Social Physique Anxiety Scale (SPAS) items, a one-dimensional instrument that assesses individual’s level of anxiety when others observe their body. Methods: In total, 152 Brazilian adults (65.8% female) answered 2 formats of the SPAS: the original with 12 items (7 regular and 5 reversed); and a new format with all items written in the same direction (i.e., regular). Both formats were filled out at different times and alternately. Differential item functioning analysis (DIF) and confirmatory factor analysis were conducted. Results: The original SPAS did not fit the data, but after allowing covariances between all reversed items, the fit improved. The wording effect was supported by the DIF, indicating a better fit to the data for the new format with all items worded in the same direction. Conclusion: The wording of the SPAS items had effect on the psychometric properties of instrument. When the wording of the reversed items was modified, the factor model fitted the data. Future studies should take these findings into account and evaluate the SPAS with all items worded in the same direction in different contexts. Level of evidence: Descriptive (cross-sectional) study, Level V.