The Batman Effect: Do weird surprises make people nicer?

DescriptionNobody expects Batman—but when he shows up in a crowded subway car, are people suddenly more likely to help a passenger in need? This week on Normal Curves, we unpack a recent quasi-experimental field study involving a caped superhero costume, a prosthetic pregnancy belly, and some puzzled Italian commuters. Along the way, we demystify three common ways of describing effects for binary outcomes—risk differences, risk ratios, and odds ratios—and explain what they actually mean in plain language. We also do some statistical sleuthing, uncover a major problem hiding in the paper’s numbers, and debate what really counts as an effective Batman outfit.Statistical topicsabsolute vs relative effectsbinary outcomescoding errorsdata errors and quality controleffect size interpretationfield experimentsoddsodds ratiospercentage differencesquasi-experimental studiesrisk differencesrisk ratiosstatistical sleuthingMethodological morals“We love an uncluttered paper, but when it's missing the basics, it's like an empty fridge. Clean, yes, but dinner is not happening.”“Before you make a fancy model, make sure the numbers in the table in the text match.”ReferencesPagnini F, Grosso F, Cavalera C, et al. Unexpected events and prosocial behavior: the Batman effect. Npj Ment Health Res. 2025;4(1):57. Published 2025 Nov 3. doi:10.1038/s44184-025-00171-5PubPeer. Comments on “Unexpected events and prosocial behavior: the Batman effect.” Accessed December 2025.Sainani KL. Understanding odds ratios. PM R. 2011;3(3):263-267. doi:10.1016/j.pmrj.2011.01.009Nuzzo RL. Communicating measures of relative risk in plain English. PM R. 2022;14(2):283-287. doi:10.1002/pmrj.12761Sainani KL. How statistics can mislead. Am J Public Health. 2012;102:e3-4.Kristin and Regina’s online courses: Demystifying Data: A Modern Approach to Statistical Understanding  Clinical Trials: Design, Strategy, and Analysis Medical Statistics Certificate Program  Writing in the Sciences Epidemiology and Clinical Research Graduate Certificate Program Programs that we teach in:Epidemiology and Clinical Research Graduate Certificate Program Find us on:Kristin -  LinkedIn & Twitter/XRegina - LinkedIn & ReginaNuzzo.com(00:00) - Intro (03:42) - Why would Batman make people nicer? (07:33) - How they ran the experiment (17:50) - Did Batman save the day? Different ways to answer that (23:00) - What are odds and odds ratios? (30:00) - Where people get it wrong (34:52) - The plot twist: big numerical errors (41:20) - Did men or women give up their seat more often? (43:49) - Wrap-up and methodological morals