Validating vignette and conjoint survey experiments against real-world behavior

TLDR

Survey experiments such as vignette and conjoint analyses are widely used to elicit stated preferences, but little is known about whether the determinants of hypothetical choices correspond to those that drive real‑world decisions. This study seeks to determine whether the attributes that predict support for naturalization in conjoint and vignette experiments align with those that influence actual referendum outcomes in Switzerland. To test this, the authors compare survey‑derived estimates of immigrant attributes with behavioral data from Swiss municipalities that used referendums to decide citizenship applications. The results show that the survey estimates, particularly from the paired conjoint design, closely match the behavioral benchmark—its estimates differ by only about 2 percentage points—while other designs exhibit notable differences.

Abstract

Survey experiments, like vignette and conjoint analyses, are widely used in the social sciences to elicit stated preferences and study how humans make multidimensional choices. However, there is a paucity of research on the external validity of these methods that examines whether the determinants that explain hypothetical choices made by survey respondents match the determinants that explain what subjects actually do when making similar choices in real-world situations. This study compares results from conjoint and vignette analyses on which immigrant attributes generate support for naturalization with closely corresponding behavioral data from a natural experiment in Switzerland, where some municipalities used referendums to decide on the citizenship applications of foreign residents. Using a representative sample from the same population and the official descriptions of applicant characteristics that voters received before each referendum as a behavioral benchmark, we find that the effects of the applicant attributes estimated from the survey experiments perform remarkably well in recovering the effects of the same attributes in the behavioral benchmark. We also find important differences in the relative performances of the different designs. Overall, the paired conjoint design, where respondents evaluate two immigrants side by side, comes closest to the behavioral benchmark; on average, its estimates are within 2% percentage points of the effects in the behavioral benchmark.