Adaptive Randomization in Conjoint Survey Experiments

Human choices are often multi-dimensional. For example, a person deciding which of two immigrants is more worthy of admission to a country might weigh the prospective immigrants' education, age, country of origin, and employment history. Conjoint experiments have rapidly generated new insight into these multidimensional choices. By independently randomizing the attributes of a pair of fictitious profiles, researchers summarize the average contribution that each attribute makes to an overall choice. But what if the effect of one attribute depends on the values of other attributes? We present a method that uses data-adaptive experimentation to search for heterogeneity in the effect of one focal attribute as a function of all other attributes. Our empirical application of this method shows that U.S. adults weigh the education of an immigrant much more heavily for certain immigrants than for others. By targeting the heterogeneous effects of a focal attribute, our approach complements conjoint designs that target the average effects of all attributes.