Most research on the compromise effect focuses on how consumers make their decisions in a complete information scenario; however, consumers generally lack sufficient information when they make purchase decisions. This research aims to explore the compromise effect with incomplete information. Three studies were conducted to examine the research hypotheses. The main findings was that consumers are more likely to choose the middle option when they have incomplete information than when they have complete information. Further, the compromise effect decreases when consumers can choose to defer their decision in an incomplete information scenario. Finally, the compromise effect decreases when consumers are asked to infer missing attribute values from the incomplete information.

Most prior research on the compromise effect has focused on single rather than multiple choices. This research investigates the potential effects of purchase quantity on the compromise effect. We propose that the share of the middle option in a trinary choice set decreases as the purchase quantity increases, because people tend to employ a balance heuristic to distribute their multiple choices among the available options to achieve a balanced state and to satisfy their variety-seeking tendency. Furthermore, we propose that the need for justification and an optimal stimulation level moderate the relationship between the number of purchase items and the compromise effect. These proposed hypotheses are supported by results from three experiments.