The Impact of Item Feature and Response Preference in a Mixed-Format Design.

A combination of positively and negatively worded items (termed a mixed-format design) has been widely adopted in personality and attitude assessments. While advocates claim that the inclusion of positively and negatively worded items will encourage respondents to process the items more carefully and avoid response preference, others have reported that negatively worded (NW) items may induce a nuisance factor and contaminate scale scores. The present study examined the extent of the impact of the NW-item feature and further investigated whether a mixed-format design could effectively control acquiescence and the preference for extreme response options using two datasets (Attitude toward Peace Walls, and International Personality Item Pool). A proposed multidimensional item response model was implemented to simultaneously estimate the impact of item feature and response preference. The results suggested that NW items induced an impact on item responses and that affirmative preference was negligible, regardless of the proportion of NW items in a scale. However, participants' extremity preference was large in both balanced and imbalanced mixed-format designs. It concludes that the impact of the NW-item feature is not negligible in a mixed-format scale, which exhibits good control of acquiescence but not extremity preference.