Demographically diverse crowds are typically not much wiser than homogeneous crowds

These studies assess the effect of social identity on judgement and are described in "Demographically diverse crowds are typically not much wiser than homogeneous crowds" (de Oliveira, S., & Nisbett, R. E. Proceedings of the National Academy of Sciences, 2018) and the article’s Supporting Information appendix. Some studies use a variety of questions to assess multiple social identity factors; the other studies are narrowed to particular social identity variables. Each study includes some type of estimation or prediction task, collects social identity variables, and asks participants to indicate their answer strategies.

Study 1 is a trivia and prediction task based on football team fan identity.

Study 2 reports on demographics plus political and religious identity and asks participants to predict vote percentages in presidential primaries.

Study 3 participants estimate the percentage of Americans that support statements on various polarizing political views and give likelihood ratings for presidential candidates to win the Iowa caucus; a variety of identity questions are asked including political and religious identity.

Study 4 includes demographics plus political and religious identity questions and asks participants to predict how the candidates would perform in the 2016 United States presidential election.

Study 5 asks participants to guess the popularity rating of books that had either gender-specific or gender-neutral appeal, and also to rate their own interest in the books. Demographic-based social identity variables such as sex are included.

Study 6 includes a wide variety of social identity variables and asks participants to estimate the likelihood of events occurring in the near future.

Study 7 participants are from diverse national backgrounds and completed judgement tasks that predicted stock prices, Olympic performance, and news events outcomes.

The data are generally interpretable when examined in conjunction with the target article. A new data file for Study 6 was uploaded on April 4, 2018 to include variables that were inadvertently left out of the original Study 6 file. A new data file for Study 7 was uploaded on April 6, 2018 to include variables that were inadvertently left out of the original Study 7 file. A codebook for this data set was added on April 6, 2018.