Does Acquiescence Affect Individual Items Consistently?

Previous research has found the effects of acquiescence to be generally consistent across item within a single survey (i.e., essential tau-equivalence), but it is unknown whether this phenomenon is consistent at the level. This article evaluated the often assumed but inadequately tested proposition that individual items are affected by acquiescence to the same degree. We modeled an external acquiescence criterion to assess (a) whether it affected scale items consistently and (b) whether it would be strongly correlated with an acquiescence factor based on an assumption of tau-equivalence. The results did not support this assumption. As further evidence, we identified a situation in which this tau-equivalence assumption could potentially be violated. We propose that the response style be best understood within a framework of an acquiescence × item interaction.