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Normal Curves: Sexy Science, Serious Statistics

Normal Curves: Sexy Science, Serious Statistics

By: Regina Nuzzo and Kristin Sainani
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 Normal Curves is a podcast about sexy science & serious statistics. Ever try to make sense of a scientific study and the numbers behind it? Listen in to a lively conversation between two stats-savvy friends who break it all down with humor and clarity. Professors Regina Nuzzo of Gallaudet University and Kristin Sainani of Stanford University discuss academic papers journal club-style — except with more fun, less jargon, and some irreverent, PG-13 content sprinkled in. Join Kristin and Regina as they dissect the data, challenge the claims, and arm you with tools to assess scientific studies on your own.©2026 Regina Nuzzo & Kristin Sainani Science Social Sciences
Episodes
  • Diagnostic Testing: Do the stats tell you what you need to know?

    Diagnostic Testing: Do the stats tell you what you need to know?
    Apr 6 2026
    Diagnostic testing: what do those statistics actually tell you? Sensitivity, specificity, positive predictive value . . . you’ve probably seen these terms before. Maybe you memorized them for a test. But do you actually know what they mean? In this episode, we take a closer look at how diagnostic tests are evaluated—and how they’re often misinterpreted. From a genetic test for cellulite to a blood test for autism, we explore how “statistically significant” findings can turn into tests that don’t actually help anyone. Along the way we meet the freckle gene, the wanderlust gene, and infidelity gene. Statistical topicsBase RateBayes RuleCase-Control StudyMatchingConditional ProbabilitySensitivitySpecificityPositive Predictive ValuePrevalenceNegative Predictive ValueFalse Positives and NegativesTrue Positives and NegativesMethodological morals“A biomarker paper is not the same thing as a biomarker test.”“If your sample doesn't match the real world, then for all of your positive predictive value needs, call on Bayes' theorem.”Detailed Show Notes with calculationsReferencesEmanuele E, Bertona M, Geroldi D. A multilocus candidate approach identifies ACE and HIF1A as susceptibility genes for cellulite. Journal of the European Academy of Dermatology and Venereology; 2010. 24: 930-35. https://genomelink.io/traits/cellulitehttps://www.genexdiagnostics.com/ Ebstein RP, Novick O, Umansky R, et al. Dopamine D4 receptor (D4DR) exon III polymorphism associated with the human personality trait of Novelty Seeking. Nat Genet. 1996;12:78-80. Kluger AN, Siegfried Z, Ebstein RP. A meta-analysis of the association between DRD4 polymorphism and novelty seeking. Mol Psychiatry. 2002;7:712-7.He Y, Martin N, Zhu G, Liu Y. Candidate genes for novelty-seeking: a meta-analysis of association studies of DRD4 exon III and COMT Val158Met. Psychiatr Genet. 2018 Dec;28(6):97-109. Smith AM, King JJ, West PR, et al. Amino Acid Dysregulation Metabotypes: Potential Biomarkers for Diagnosis and Individualized Treatment for Subtypes of Autism Spectrum Disorder. Biol Psychiatry. 2019;85:345-54.Sainani K, Goodman S. Lack of Diagnostic Utility of “Amino Acid Dysregulation Metabotypes.”Biol Psychiatry. 2018; 85: e41-e42.Kristin and Regina’s online coursesDemystifying 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) - Introduction (02:24) - The Cellulite Test (06:41) - Understanding Sensitivity and Specificity (12:50) - Enter Positive Predictive Value (18:40) - Why Base Rates Matter (24:06) - More Ridiculous Tests (33:30) - The Wanderlust Gene Deep Dive (41:27) - The NeuroPoint Autism Test (53:34) - Trying to Set the Record Straight (01:02:39) - Personal Stories (01:05:54) - Wrap-up
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    1 hr and 9 mins
  • Epidurals: Are labor epidurals really linked to autism?

    Epidurals: Are labor epidurals really linked to autism?
    Mar 23 2026
    Epidurals are widely used and widely trusted for pain relief during labor. So when a 2020 study reported that they might be linked to autism, it raised a troubling question: could a routine medical decision have long-term consequences? We follow that claim from headline to evidence—and watch what happens when other scientists take a closer look. We dig into the original study, a wave of replication studies from around the world, and a meta-analysis that tries to make sense of it all. Along the way, we unpack hazard ratios, Cox regression, inverse probability weighting, and sibling analyses—and why even sophisticated statistical adjustment can’t eliminate confounding. Plus: why bigger datasets don’t solve everything, what happens when results shrink after adjustment, and how a controversial study turned into a case study in science working as it should. Bonus: our first guest journalist interview!Statistical topicsConfoundingCox regressionHazard ratiosInverse probability weighting (IPTW)Multivariable adjustmentObservational studiesResidual confoundingRetrospective cohort studiesSibling analysisStatistical adjustmentStatistical significance vs practical significanceSurvival analysisMethodological morals“Every time you adjust the model and the effect gets smaller, that's the universe whispering, maybe don't build a causal story out of this.”“Consistency across studies is gold.”“There's more to the story than the statistics.”ReferencesDattaro, Laura. A questionable study linked autism to epidurals. Then what? Spectrum. April 18, 2023. Dattaro, Laura. How to find baby sharks. Nautilus. September 9. 2024.Laura Dattaro’s home page.Phil Kearney’s blog post about the SMART framework.Qiu C, Lin JC, Shi JM, et al. Association Between Epidural Analgesia During Labor and Risk of Autism Spectrum Disorders in Offspring. JAMA Pediatr. 2020;174:1168-1175. Joint Statement. Labor Epidurals Do Not Cause Autism; Safe for Mothers and Infants, say Anesthesiology, Obstetrics, and Pediatric Medical Societies. American Society of Anesthesiologists. October 12, 2020.Wall-Wieler E, Bateman BT, Hanlon-Dearman A, Roos LL, Butwick AJ. Association of Epidural Labor Analgesia With Offspring Risk of Autism Spectrum Disorders. JAMA Pediatr. 2021;175:698-705. Christakis DA. More on epidurals and autism. JAMA Pediatrics. 2021; 175: 705.Mikkelsen AP, Greiber IK, Scheller NM, Lidegaard Ø. Association of Labor Epidural Analgesia With Autism Spectrum Disorder in Children. JAMA. 2021;326:1170–1177. Hanley GE, Bickford C, Ip A, et al. Association of Epidural Analgesia During Labor and Delivery With Autism Spectrum Disorder in Offspring. JAMA. 2021;326:1178-1185. Hegvik TA, Klungsøyr K, Kuja-Halkola R, et al. Labor epidural analgesia and subsequent risk of offspring autism spectrum disorder and attention-deficit/hyperactivity disorder: a cross-national cohort study of 4.5 million individuals and their siblings. Am J Obstet Gynecol. 2023;228:233.e1-233.e12. Epub 2022 Aug 13. Hu X, Wang B, Chen J, Han D, Wu J. Association Between Epidural Labor Analgesia and Autism Spectrum Disorder in Offspring: A Systematic Review and Meta-Analysis. J Pain Res;17:227-240. 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 (01:40) - Why autism is hard to study (05:18) - The original 2020 study (11:38) - Results & hazard ratios (15:24) - Confounding & adjustment (27:29) - Criticism & plausibility (35:08) - Replications begin (45:57) - Converging evidence & meta-analysis (52:07) - What does it mean? (54:57) - Guest & wrap-up
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    1 hr and 11 mins
  • Daylight Saving Time: Does springing forward cause heart attacks?

    Daylight Saving Time: Does springing forward cause heart attacks?
    Mar 9 2026
    Every year we spring forward and lose an hour of sleep. But do we also lose a few heart cells? Some headlines claim that heart attacks spike by 24% after daylight saving time begins. In this episode we trace that number back to the research behind it—and what we find is more complicated than the headlines suggest. We examine a famous New England Journal of Medicine letter, a large international meta-analysis, and a massive modern U.S. registry study. Along the way we talk about incidence ratios, relative versus absolute risk, negative controls, and a haunting concept called harvesting. Plus: why bar charts are not for numerical data, why journalists love dramatic numbers, and how a bug collector helped invent daylight saving time.Statistical topicsIncidence ratios / incidence ratesMeta-analysisNegative controlsRelative risk vs absolute riskStatistical vs practical significanceStatistical SleuthingMethodological morals“A bump in time isn’t always a bump in total.” “If you already know the story you want to tell, you can always find a number to tell it.” ReferencesBourke, India. “An obsessed insect hunter: The creepy-crawly origins of daylight saving.” BBC Future, March 31, 2024. https://www.bbc.com/future/article/20240308-how-first-suggestions-of-daylight-savings-time-was-inspired-by-insectsFox-Skelly, Jasmin. “How Daylight Saving Time Affects Your Health.” BBC Future, October 25, 2025. https://www.bbc.com/future/article/20251024-how-daylight-saving-time-affects-our-healthHurst A, Morfeld P, Lewis P, Erren TC. Daylight Saving Time Transitions and Risk of Heart Attack. Dtsch Arztebl Int. 2024;121(15):490-496. doi:10.3238/arztebl.m2024.0078Janszky I, Ljung R. Shifts to and from daylight saving time and incidence of myocardial infarction. N Engl J Med. 2008;359(18):1966-1968. doi:10.1056/NEJMc0807104Jiddou MR, Pica M, Boura J, Qu L, Franklin BA. Incidence of myocardial infarction with shifts to and from daylight savings time. Am J Cardiol. 2013;111(5):631-635. doi:10.1016/j.amjcard.2012.11.010Mellour, Richard. “The builder who changed how the world keeps time.” BBC Future, March 11, 2016. https://www.bbc.com/future/article/20160310-the-builder-who-changed-how-the-world-keeps-timeRymer JA, Li S, Chiswell K, et al. Daylight Savings Time and Acute Myocardial Infarction. JAMA Netw Open. 2025;8(9):e2530442. Published 2025 Sep 2. doi:10.1001/jamanetworkopen.2025.30442https://graph2table.com/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 (05:03) - Strange history of daylight saving time (16:06) - Swedish NEJM study (19:14) - Incidence ratios explained (22:13) - What the Swedish study actually found (31:11) - Absolute vs relative risk (34:27) - Harvesting effect (40:10) - 2024 Meta-analysis (45:37) - Large modern US study (55:23) - Where the “24% increase” came from (59:16) - Wrap-up
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    1 hr and 5 mins
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