Number of answer categories for bipolar item specific scales in face-to-face surveys: Does more mean better?

Since decades, surveys have been the main source of data in a considerable amount of studies. Designing surveys implies taking many decisions which affect the data quality and thus the results. In this paper, we focus on one of these decisions: the number of answer categories in bipolar closed-ended item specific attitudinal questions. We investigate the measurement quality (product of reliability and validity) of such scales using data from three Multitrait-Multimethod experiments implemented in the European Survey Social (face-to-face): two about social trust (rounds 1 and 4), and one about immigration (round 6). Data are analyzed using the Estimation Using Pooled Data procedure (Saris and Satorra in Struct. Equ. Modeling 25(5): 659–672, 2018). The results show that, out of the three scales tested, the 11-point scale has higher quality in the immigration experiment whereas in the social trust experiments, the 6-point is the one with the highest quality.