External Validity of Hypothetical Surveys and Laboratory Experiments

We compare the ability of three preference elicitation methods (hypothetical choices, non-hypothetical choices, and non-hypothetical rankings) and three discrete-choice econometric models (the multinomial logit, the independent availability logit, and the random parameter logit) to predict actual retail shopping behavior in three different product categories (ground beef, wheat flour, and dishwashing liquid). Overall, across all methods, we find a reasonably high level of external validity. Our results suggest that the non-hypothetical elicitation approaches, especially the non-hypothetical ranking, outperformed the hypothetical choice experiment in predicting retail sales. We also find that the random parameter logit can have superior predictive performance, but that the multinomial logit predicts equally well in some circumstances.