{ "schemaVersion": 1, "verifiedDate": "2026-10-31", "scope": "Selected U.S. historical polling case studies and one-firm presidential final-estimate record. Not an exhaustive census or greatest-ever ranking.", "definitions": { "pollingUpset": "An outcome that reverses the leader in the specified poll or materially differs from its estimated margin. The comparator and dates must be named.", "politicalUpset": "An outcome surprising relative to a stated prior expectation. It need not be a polling failure; accurate polls may anticipate an unexpected political result.", "signedError": "Specified poll Democratic-minus-Republican margin minus outcome Democratic-minus-Republican margin; positive means Democratic overstatement.", "normalization": "100*(D-R)/(D+R), separately for poll shares and election shares. Two-party normalized margins are distinct from raw margins in the AAPOR main series." }, "gallupSeries": { "label": "Gallup final national presidential estimates, 1936–2012", "recommendedChartMetric": "normalizedAbsoluteError", "metricLabel": "Absolute error in two-party normalized D–R margin, percentage points", "provenance": "Final estimates transcribed from APP Gallup table, with primary Gallup corroboration for 2004/2008/2012; modern outcomes replaced with FEC counts.", "limitations": [ "One firm and one final estimate per election; not average performance across all pollsters.", "Pre 1952 quota sampling, later probability methods, survey modes, likely-voter models and undecided allocation change over time.", "Historical numbers are often allocated estimates rather than unallocated poll responses. Normalization harmonizes a denominator but cannot remove design changes.", "Pre 2000 outcomes use rounded source shares and can differ slightly from later revised counts. Do not overstate precision of derived errors.", "Fieldwork windows are not uniform; historical date fields remain null where not independently verified.", "Do not join this series to AAPOR's final-two-week across-poll means as though it were one continuous metric." ], "rows": [ { "year": 1936, "democrat": "Franklin D. Roosevelt", "republican": "Alf Landon", "pollDemShare": 55.7, "pollRepShare": 44.3, "actualDemShare": 60.8, "actualRepShare": 36.5, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": 11.400000000000006, "actualRawMargin": 24.299999999999997, "normalizedPollMargin": 11.400000000000004, "normalizedActualMargin": 24.974306269270294, "normalizedSignedError": -13.57430626927029, "normalizedAbsoluteError": 13.57430626927029, "reportedShareMeanAbsoluteError": 6.449999999999996 }, { "year": 1940, "democrat": "Franklin D. Roosevelt", "republican": "Wendell Willkie", "pollDemShare": 52, "pollRepShare": 48, "actualDemShare": 54.7, "actualRepShare": 44.8, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": 4, "actualRawMargin": 9.900000000000006, "normalizedPollMargin": 4.0, "normalizedActualMargin": 9.9497487437186, "normalizedSignedError": -5.949748743718599, "normalizedAbsoluteError": 5.949748743718599, "reportedShareMeanAbsoluteError": 2.950000000000003 }, { "year": 1944, "democrat": "Franklin D. Roosevelt", "republican": "Thomas Dewey", "pollDemShare": 51.5, "pollRepShare": 48.5, "actualDemShare": 53.4, "actualRepShare": 45.9, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": 3.0, "actualRawMargin": 7.5, "normalizedPollMargin": 3.0, "normalizedActualMargin": 7.552870090634442, "normalizedSignedError": -4.552870090634442, "normalizedAbsoluteError": 4.552870090634442, "reportedShareMeanAbsoluteError": 2.25 }, { "year": 1948, "democrat": "Harry Truman", "republican": "Thomas Dewey", "pollDemShare": 44.5, "pollRepShare": 49.5, "actualDemShare": 49.5, "actualRepShare": 45.1, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": -5.0, "actualRawMargin": 4.399999999999999, "normalizedPollMargin": -5.319148936170213, "normalizedActualMargin": 4.651162790697674, "normalizedSignedError": -9.970311726867887, "normalizedAbsoluteError": 9.970311726867887, "reportedShareMeanAbsoluteError": 4.699999999999999 }, { "year": 1952, "democrat": "Adlai Stevenson", "republican": "Dwight Eisenhower", "pollDemShare": 49, "pollRepShare": 51, "actualDemShare": 44.4, "actualRepShare": 55.1, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": -2, "actualRawMargin": -10.700000000000003, "normalizedPollMargin": -2.0, "normalizedActualMargin": -10.753768844221108, "normalizedSignedError": 8.753768844221108, "normalizedAbsoluteError": 8.753768844221108, "reportedShareMeanAbsoluteError": 4.350000000000001 }, { "year": 1956, "democrat": "Adlai Stevenson", "republican": "Dwight Eisenhower", "pollDemShare": 40.5, "pollRepShare": 59.5, "actualDemShare": 42, "actualRepShare": 57.4, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": -19.0, "actualRawMargin": -15.399999999999999, "normalizedPollMargin": -19.0, "normalizedActualMargin": -15.49295774647887, "normalizedSignedError": -3.5070422535211296, "normalizedAbsoluteError": 3.5070422535211296, "reportedShareMeanAbsoluteError": 1.8000000000000007 }, { "year": 1960, "democrat": "John F. Kennedy", "republican": "Richard Nixon", "pollDemShare": 51, "pollRepShare": 49, "actualDemShare": 49.7, "actualRepShare": 49.5, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": 2, "actualRawMargin": 0.20000000000000284, "normalizedPollMargin": 2.0, "normalizedActualMargin": 0.2016129032258093, "normalizedSignedError": 1.7983870967741906, "normalizedAbsoluteError": 1.7983870967741906, "reportedShareMeanAbsoluteError": 0.8999999999999986 }, { "year": 1964, "democrat": "Lyndon Johnson", "republican": "Barry Goldwater", "pollDemShare": 64, "pollRepShare": 36, "actualDemShare": 61.1, "actualRepShare": 38.5, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": 28, "actualRawMargin": 22.6, "normalizedPollMargin": 28.0, "normalizedActualMargin": 22.690763052208837, "normalizedSignedError": 5.309236947791163, "normalizedAbsoluteError": 5.309236947791163, "reportedShareMeanAbsoluteError": 2.6999999999999993 }, { "year": 1968, "democrat": "Hubert Humphrey", "republican": "Richard Nixon", "pollDemShare": 42, "pollRepShare": 43, "actualDemShare": 42.7, "actualRepShare": 43.4, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": -1, "actualRawMargin": -0.6999999999999957, "normalizedPollMargin": -1.1764705882352942, "normalizedActualMargin": -0.8130081300812959, "normalizedSignedError": -0.36346245815399825, "normalizedAbsoluteError": 0.36346245815399825, "reportedShareMeanAbsoluteError": 0.5500000000000007 }, { "year": 1972, "democrat": "George McGovern", "republican": "Richard Nixon", "pollDemShare": 38, "pollRepShare": 62, "actualDemShare": 37.5, "actualRepShare": 60.7, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": -24, "actualRawMargin": -23.200000000000003, "normalizedPollMargin": -24.0, "normalizedActualMargin": -23.62525458248473, "normalizedSignedError": -0.37474541751527113, "normalizedAbsoluteError": 0.37474541751527113, "reportedShareMeanAbsoluteError": 0.8999999999999986 }, { "year": 1976, "democrat": "Jimmy Carter", "republican": "Gerald Ford", "pollDemShare": 48, "pollRepShare": 49, "actualDemShare": 50.1, "actualRepShare": 48, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": -1, "actualRawMargin": 2.1000000000000014, "normalizedPollMargin": -1.0309278350515463, "normalizedActualMargin": 2.1406727828746193, "normalizedSignedError": -3.1716006179261655, "normalizedAbsoluteError": 3.1716006179261655, "reportedShareMeanAbsoluteError": 1.5500000000000007 }, { "year": 1980, "democrat": "Jimmy Carter", "republican": "Ronald Reagan", "pollDemShare": 44, "pollRepShare": 47, "actualDemShare": 41, "actualRepShare": 50.7, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": -3, "actualRawMargin": -9.700000000000003, "normalizedPollMargin": -3.2967032967032965, "normalizedActualMargin": -10.577971646673939, "normalizedSignedError": 7.2812683499706425, "normalizedAbsoluteError": 7.2812683499706425, "reportedShareMeanAbsoluteError": 3.3500000000000014 }, { "year": 1984, "democrat": "Walter Mondale", "republican": "Ronald Reagan", "pollDemShare": 41, "pollRepShare": 59, "actualDemShare": 40.6, "actualRepShare": 58.8, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": -18, "actualRawMargin": -18.199999999999996, "normalizedPollMargin": -18.0, "normalizedActualMargin": -18.309859154929573, "normalizedSignedError": 0.3098591549295726, "normalizedAbsoluteError": 0.3098591549295726, "reportedShareMeanAbsoluteError": 0.3000000000000007 }, { "year": 1988, "democrat": "Michael Dukakis", "republican": "George H. W. Bush", "pollDemShare": 44, "pollRepShare": 56, "actualDemShare": 45.6, "actualRepShare": 53.4, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": -12, "actualRawMargin": -7.799999999999997, "normalizedPollMargin": -12.0, "normalizedActualMargin": -7.878787878787876, "normalizedSignedError": -4.121212121212124, "normalizedAbsoluteError": 4.121212121212124, "reportedShareMeanAbsoluteError": 2.1000000000000014 }, { "year": 1992, "democrat": "Bill Clinton", "republican": "George H. W. Bush", "pollDemShare": 49, "pollRepShare": 37, "actualDemShare": 43, "actualRepShare": 37.4, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": 12, "actualRawMargin": 5.600000000000001, "normalizedPollMargin": 13.953488372093023, "normalizedActualMargin": 6.965174129353235, "normalizedSignedError": 6.988314242739788, "normalizedAbsoluteError": 6.988314242739788, "reportedShareMeanAbsoluteError": 3.1999999999999993 }, { "year": 1996, "democrat": "Bill Clinton", "republican": "Bob Dole", "pollDemShare": 52, "pollRepShare": 41, "actualDemShare": 49.2, "actualRepShare": 40.7, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualPrecision": "Source-reported shares, rounded to 0.1 percentage point; derived errors are approximate.", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "reportedMargin": 11, "actualRawMargin": 8.5, "normalizedPollMargin": 11.827956989247312, "normalizedActualMargin": 9.454949944382646, "normalizedSignedError": 2.373007044864666, "normalizedAbsoluteError": 2.373007044864666, "reportedShareMeanAbsoluteError": 1.5499999999999972 }, { "year": 2000, "democrat": "Al Gore", "republican": "George W. Bush", "pollDemShare": 46, "pollRepShare": 48, "actualDemShare": 48.38465785811123, "actualRepShare": 47.86865341430348, "pollSource": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "actualSource": "https://www.fec.gov/documents/1732/FederalElections2000_PresidentialGeneralElectionResultsbyState.pdf", "actualPrecision": "Calculated from exact FEC published vote counts", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": null, "fieldEnd": null, "datePrecision": "Final published estimate for this election; uniform fieldwork window not established.", "demVotes": 50999897, "repVotes": 50456002, "totalVotes": 105405100, "reportedMargin": -2, "actualRawMargin": 0.516004443807752, "normalizedPollMargin": -2.127659574468085, "normalizedActualMargin": 0.5360900700313195, "normalizedSignedError": -2.6637496444994047, "normalizedAbsoluteError": 2.6637496444994047, "reportedShareMeanAbsoluteError": 1.258002221903876 }, { "year": 2004, "democrat": "John Kerry", "republican": "George W. Bush", "pollDemShare": 49, "pollRepShare": 49, "actualDemShare": 48.2671225139436, "actualRepShare": 50.73014839608163, "pollSource": "https://news.gallup.com/poll/13873/final-poll-shows-presidential-race-dead-heat.aspx", "actualSource": "https://www.fec.gov/documents/1630/2004tables.pdf", "actualPrecision": "Calculated from exact FEC published vote counts", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": "2004-10-29", "fieldEnd": "2004-10-31", "datePrecision": "Verified primary release", "demVotes": 59028444, "repVotes": 62040610, "totalVotes": 122295345, "allocationNote": "Allocated final estimate 49/49. Unallocated likely-voter poll was Bush 49/Kerry 47.", "reportedMargin": 0, "actualRawMargin": -2.4630258821380338, "normalizedPollMargin": 0.0, "normalizedActualMargin": -2.487973516337215, "normalizedSignedError": 2.487973516337215, "normalizedAbsoluteError": 2.487973516337215, "reportedShareMeanAbsoluteError": 1.2315129410690169 }, { "year": 2008, "democrat": "Barack Obama", "republican": "John McCain", "pollDemShare": 55, "pollRepShare": 44, "actualDemShare": 52.92551537987396, "actualRepShare": 45.652714238303325, "pollSource": "https://news.gallup.com/poll/111703/final-presidential-estimate-obama-55-mccain-44.aspx", "actualSource": "https://www.fec.gov/documents/1669/tables2008.pdf", "actualPrecision": "Calculated from exact FEC published vote counts", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": "2008-10-31", "fieldEnd": "2008-11-02", "datePrecision": "Verified primary release", "demVotes": 69498516, "repVotes": 59948323, "totalVotes": 131313820, "allocationNote": "Allocated final estimate 55/44. Unallocated likely-voter poll was Obama 53/McCain 42.", "reportedMargin": 11, "actualRawMargin": 7.272801141570632, "normalizedPollMargin": 11.11111111111111, "normalizedActualMargin": 7.377695024287155, "normalizedSignedError": 3.733416086823956, "normalizedAbsoluteError": 3.733416086823956, "reportedShareMeanAbsoluteError": 1.863599429214684 }, { "year": 2012, "democrat": "Barack Obama", "republican": "Mitt Romney", "pollDemShare": 49, "pollRepShare": 50, "actualDemShare": 51.06370658000776, "actualRepShare": 47.20402096565367, "pollSource": "https://news.gallup.com/poll/158519/romney-obama-gallup-final-election-survey.aspx", "actualSource": "https://www.fec.gov/documents/1683/2012pres.pdf", "actualPrecision": "Calculated from exact FEC published vote counts", "seriesType": "One firm: final Gallup national estimate, not an industry average", "fieldStart": "2012-11-01", "fieldEnd": "2012-11-04", "datePrecision": "Verified primary release", "demVotes": 65915795, "repVotes": 60933504, "totalVotes": 129085410, "allocationNote": "Allocated final estimate Obama 49/Romney 50. Unallocated likely-voter poll was Obama 48/Romney 49.", "reportedMargin": -1, "actualRawMargin": 3.859685614354092, "normalizedPollMargin": -1.0101010101010102, "normalizedActualMargin": 3.9277245040195283, "normalizedSignedError": -4.937825514120538, "normalizedAbsoluteError": 4.937825514120538, "reportedShareMeanAbsoluteError": 2.429842807177046 } ] }, "cases": [ { "slug": "1936-literary-digest", "year": 1936, "title": "1936: millions of returns, the wrong electorate", "office": "President", "democrat": "Franklin D. Roosevelt", "republican": "Alf Landon", "pollDemShare": 42.92383279375055, "pollRepShare": 57.07616720624945, "actualDemShare": 62.45644361079059, "actualRepShare": 37.54355638920941, "pollMargin": -14.152334412498902, "actualMargin": 24.912887221581187, "signedError": -39.06522163408009, "absoluteError": 39.06522163408009, "marginDefinition": "Democratic share minus Republican share, percentage points", "pollster": "Literary Digest", "sponsor": "Literary Digest", "publicationDate": "1936-10-31", "fieldStart": null, "fieldEnd": null, "fieldWindow": "Cards mailed in late summer; cumulative returns published through October 31, 1936. Exact field cutoff not established.", "pollN": 2376523, "pollDemResponses": 972897, "pollRepResponses": 1293669, "chartBasis": "Two-party normalized shares on BOTH sides; third parties excluded from poll and outcome denominators.", "result": { "demVotes": 27747636, "repVotes": 16679543, "totalVotes": 45642303, "sourcePrecision": "Arkansas Secretary of State historical compilation, published 2010; historical totals can differ slightly across editions." }, "classification": "Wrong leader in a national straw poll", "takeaway": "A huge voluntary return cannot guarantee a representative sample.", "analysis": [ { "status": "established", "text": "The original published Digest count favored Landon; Roosevelt won decisively. Normalizing both to two-party shares puts their comparison on the same denominator." }, { "status": "supported, contribution uncertain", "text": "Historical reanalyses identify selective participation and coverage differences. The familiar explanation that telephone and automobile ownership alone caused the miss is incomplete." }, { "status": "comparison", "text": "Gallup's separate final estimate was Roosevelt 55.7/Landon 44.3. It identified the winner while understating Roosevelt's two-party margin; a correct winner call is not zero numerical error." } ], "secondaryPolls": [ { "pollster": "Gallup", "pollDemShare": 55.7, "pollRepShare": 44.3, "basis": "Allocated two-party final estimate", "source": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences" } ], "sources": [ { "label": "Literary Digest, October 31, 1936: original issue scan", "url": "https://www.rossmanchance.com/chance/LD/LitDigest1936.pdf", "kind": "primary historical document", "detail": "Original magazine pages hosted by statistics educator Beth Chance. HTTPS access verified with the system trust store; no certificate-warning bypass was used." }, { "label": "Arkansas Secretary of State Historical Report 2010, printed p. 585", "url": "https://www.sos.arkansas.gov/uploads/elections/historical_report1210.pdf", "kind": "official historical compilation", "detail": "" }, { "label": "Squire 1988, Why the 1936 Literary Digest Poll Failed", "url": "https://doi.org/10.1086/269085", "kind": "original empirical research", "detail": "Publisher access may be restricted; direct automated access returned 403. The institutional teaching mirror below provides the same original research article." }, { "label": "Lusinchi 2012, President Landon and the 1936 Literary Digest poll", "url": "https://pdixon.stat.iastate.edu/stat587/resources/president-landon-and-the-1936-literary-digest-poll-were-automobile-and-telephone-owners-to-blame.pdf", "kind": "original empirical research", "detail": "" }, { "label": "Squire 1988, original article: institutional teaching mirror", "url": "https://www.michaelperess.com/teaching/sscs2022/Squire.pdf", "kind": "original empirical research, teaching mirror", "detail": "The original Public Opinion Quarterly article, pages 125–133, with publication attribution preserved." } ], "normalizedPollMargin": -14.152334412498904, "normalizedActualMargin": 24.912887221581187, "normalizedSignedError": -39.06522163408009 }, { "slug": "1948-truman-dewey", "year": 1948, "title": "1948: the Dewey lead that disappeared", "office": "President", "democrat": "Harry Truman", "republican": "Thomas Dewey", "pollDemShare": 44.5, "pollRepShare": 49.5, "actualDemShare": 49.5, "actualRepShare": 45.1, "pollMargin": -5.0, "actualMargin": 4.399999999999999, "signedError": -9.399999999999999, "absoluteError": 9.399999999999999, "marginDefinition": "Democratic share minus Republican share, percentage points", "pollster": "Gallup", "sponsor": "American Institute of Public Opinion", "publicationDate": "1948-11-01", "fieldStart": null, "fieldEnd": null, "fieldWindow": "Final published estimate. October 15–25 fieldwork is commonly reported in historical compilations but was not independently established from an original release here.", "chartBasis": "Reported shares; outcome rounded to 0.1 pp. Poll allocated to four principal candidates; actual table includes minor candidates. Use normalized comparison if denominator identity is required.", "result": { "demVotes": 24179347, "repVotes": 21991292, "totalVotes": null, "sourcePrecision": "Candidate counts independently corroborated by Truman Presidential Library. All-vote total not reconciled here; displayed shares use the cited rounded historical table." }, "classification": "Wrong leader in final national estimate", "takeaway": "The sampling and timing of a poll matter more than confidence in its winner call.", "analysis": [ { "status": "established", "text": "The three major polling organizations used quota sampling and all picked Dewey. The selected Gallup estimate favored Dewey by 5 points; the cited rounded outcome favored Truman by 4.4." }, { "status": "supported", "text": "AAPOR's methodological review describes how interviewer choices within quotas overrepresented more educated and affluent respondents, creating bias against Truman." }, { "status": "institutional retrospective, not exclusive cause", "text": "Gallup's retrospective also attributes part of the miss to interviewing ending before late movement toward Truman. This does not establish that a late swing alone explains the error." }, { "status": "caution", "text": "A newspaper headline is not a poll. Evaluate each survey separately from the Chicago Tribune's premature election call." } ], "sources": [ { "label": "Gallup final estimate and historical result table", "url": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "kind": "academic compilation", "detail": "" }, { "label": "AAPOR Task Force on Nonprobability Sampling, printed p. 12", "url": "https://aapor.org/wp-content/uploads/2022/11/NPS_TF_Report_Final_7_revised_FNL_6_22_13.pdf", "kind": "professional methodological review", "detail": "" }, { "label": "Gallup institutional retrospective", "url": "https://news.gallup.com/poll/3376/George-Gallup-TwentiethCentury-Pioneer.aspx", "kind": "pollster retrospective", "detail": "" }, { "label": "Truman Presidential Library 1948 election educational sheet", "url": "https://www.trumanlibrary.gov/public/1948_election.pdf", "kind": "official presidential library", "detail": "" } ], "normalizedPollMargin": -5.319148936170213, "normalizedActualMargin": 4.651162790697674, "normalizedSignedError": -9.970311726867887 }, { "slug": "1980-reagan-carter", "year": 1980, "title": "1980: the right winner, a much larger victory", "office": "President", "democrat": "Jimmy Carter", "republican": "Ronald Reagan", "pollDemShare": 44, "pollRepShare": 47, "actualDemShare": 41.01461290840371, "actualRepShare": 50.747316475097485, "pollMargin": -3, "actualMargin": -9.732703566693772, "signedError": 6.732703566693772, "absoluteError": 6.732703566693772, "marginDefinition": "Democratic share minus Republican share, percentage points", "pollster": "Gallup", "sponsor": "Gallup", "publicationDate": null, "fieldStart": null, "fieldEnd": null, "fieldWindow": "Final Gallup estimate immediately before November 4, 1980; exact original field dates not verified here.", "chartBasis": "Final allocated published shares versus all-vote shares from official historical compilation.", "result": { "demVotes": 35483883, "repVotes": 43904153, "totalVotes": 86515221, "sourcePrecision": "Arkansas Secretary of State historical compilation, published 2010. Counts differ slightly from other historical editions." }, "classification": "Large margin underestimate; final poll leader won", "takeaway": "Calling the winner correctly can conceal a substantial error in the victory margin.", "analysis": [ { "status": "established", "text": "Gallup's final estimate put Reagan ahead 47–44. The result was approximately 51–41, a much wider win." }, { "status": "pollster interpretation", "text": "Gallup's retrospective traces movement toward Reagan after the October 28 debate and discusses the Iran hostage crisis. This is evidence of changing measured preferences, not an identified causal effect of the debate." }, { "status": "methodological context; abstract verified", "text": "Fenwick and colleagues studied how to allocate undecided respondents in 1980 presidential polls and validated their method with a post-election follow-up. The verified abstract does not establish why this particular final Gallup estimate missed." } ], "sources": [ { "label": "Gallup historical final-estimate table", "url": "https://www.presidency.ucsb.edu/statistics/data/election-year-presidential-preferences", "kind": "academic compilation", "detail": "" }, { "label": "Gallup 2008, Late Upsets Are Rare, but Have Happened", "url": "https://news.gallup.com/poll/111451/late-upsets-rare-happened.aspx", "kind": "pollster retrospective", "detail": "" }, { "label": "George Gallup’s November 1980 postmortem", "url": "https://www.washingtonpost.com/archive/politics/1980/11/12/what-happened-to-the-polls/a5abac1c-ccb0-4828-8902-60b99ec5d401/", "kind": "first-person contemporary pollster assessment", "detail": "Gallup attributed the miss to timing. This is his interpretation." }, { "label": "Fenwick, Wiseman, Becker and Heiman 1982, Classifying Undecided Voters in Pre-Election Polls", "url": "https://academic.oup.com/poq/article-abstract/46/3/383/1811208", "kind": "peer-reviewed original methodological research", "detail": "The publisher abstract describes allocation of undecided respondents in 1980 presidential polls and validation using a post-election follow-up. Only the abstract was verified; automated publisher access may return 403 and the full article may require access. This is methodological context, not an audit establishing this Gallup estimate’s cause." }, { "label": "Arkansas Secretary of State Historical Report 2010, printed p. 586", "url": "https://www.sos.arkansas.gov/uploads/elections/historical_report1210.pdf", "kind": "official historical compilation", "detail": "" } ], "normalizedPollMargin": -3.2967032967032965, "normalizedActualMargin": -10.60647223972136, "normalizedSignedError": 7.309768943018063 }, { "slug": "1982-california-governor", "year": 1982, "title": "1982 California: a famous label, several explanations", "office": "Governor", "democrat": "Tom Bradley", "republican": "George Deukmejian", "pollDemShare": 49, "pollRepShare": 42, "actualDemShare": 48.08701565046673, "actualRepShare": 49.27209345845175, "pollMargin": 7, "actualMargin": -1.1850778079850173, "signedError": 8.185077807985017, "absoluteError": 8.185077807985017, "marginDefinition": "Democratic share minus Republican share, percentage points", "pollster": "Field Institute / California Poll", "sponsor": "California Poll media subscribers", "publicationDate": null, "fieldStart": "1982-10-29", "fieldEnd": "1982-10-31", "fieldWindow": "October 29–31, 1982 final Field survey, reproduced in Nieman Reports Spring 1983.", "chartBasis": "Reported final poll candidate shares versus all counted gubernatorial votes.", "result": { "demVotes": 3787669, "repVotes": 3881014, "totalVotes": 7876698, "sourcePrecision": "Official returns reproduced in Field Institute release 1201, February 1, 1983. Absentee/precinct splits include estimates for 2 counties; statewide candidate totals are the published official totals." }, "classification": "Wrong leader in final statewide poll", "takeaway": "The Bradley effect is a hypothesis about mechanisms, not a complete explanation established by the miss itself.", "analysis": [ { "status": "established", "text": "Field's final survey favored Bradley 49–42; the official count reproduced in Field's audit gave Deukmejian 3,881,014 votes to Bradley 3,787,669." }, { "status": "documented arithmetic", "text": "Field's audit reports Bradley ahead by 19,429 among precinct voters and Deukmejian ahead by 112,774 among absentee voters, producing the 93,345-vote statewide margin. Two county absentee splits were estimated." }, { "status": "pollster interpretation; multiple causes", "text": "Field's February 1983 assessment discusses Republican absentee mobilization, the handgun initiative, minority turnout and racial bias. These are its post-election interpretations rather than a randomized decomposition of polling error." }, { "status": "uncertain", "text": "The result alone cannot show that respondents concealed their preferences because of race. Timing, turnout, undecided allocation and sample composition are competing or interacting explanations." } ], "sources": [ { "label": "Field Institute original release 1201, February 1, 1983, pp 1–2", "url": "https://abcnews.go.com/images/PollingUnit/FieldPoll1982analysis.pdf", "kind": "primary pollster audit", "detail": "" }, { "label": "Nieman Reports Spring 1983, Bradley vs. Deukmejian table, source: Field Institute", "url": "https://niemanreports.org/app/uploads/2025/09/Spring-1983_150.pdf", "kind": "contemporary research using original polling data", "detail": "Poll 49/42 and October 29–31 dates verified from indexed table. Table's preliminary outcome percentages are not used." } ], "normalizedPollMargin": 7.6923076923076925, "normalizedActualMargin": -1.2172233485202046, "normalizedSignedError": 8.909531040827897 }, { "slug": "2014-virginia-senate", "year": 2014, "title": "2014 Virginia: the winner was right, the margin was not", "office": "U.S. Senate", "democrat": "Mark Warner", "republican": "Ed Gillespie", "pollDemShare": 49, "pollRepShare": 40, "actualDemShare": 49.14887481002692, "actualRepShare": 48.33739219599729, "pollMargin": 9, "actualMargin": 0.8114826140296287, "signedError": 8.188517385970371, "absoluteError": 8.188517385970371, "marginDefinition": "Democratic share minus Republican share, percentage points", "pollster": "Public Policy Polling", "sponsor": "League of Conservation Voters Action Fund", "publicationDate": null, "fieldStart": "2014-10-29", "fieldEnd": "2014-10-30", "pollN": 937, "population": "Likely voters", "publishedShareMOE": 3.2, "fieldWindow": "October 29–30, 2014; the final PPP release located for this race. Sponsor is an advocacy organization.", "chartBasis": "Reported likely-voter shares versus current Virginia Department of Elections all-vote totals.", "result": { "demVotes": 1073667, "repVotes": 1055940, "totalVotes": 2184520, "sourcePrecision": "Current state historical archive; includes 1,811 write-ins. Earlier FEC edition used 1,764 write-ins and total 2,184,473." }, "classification": "Large Democratic-margin overestimate; same winner", "takeaway": "A nearly correct estimate of the winner's share can still produce a badly wrong margin.", "analysis": [ { "status": "established", "text": "The selected PPP poll put Warner at 49 and Gillespie at 40; Warner finished near 49.15 while Gillespie finished near 48.34. The published margin missed by about 8.2 points even though the poll's leader won." }, { "status": "arithmetic, not voter-flow evidence", "text": "Warner's estimated share changed little in the comparison; the numerical miss is concentrated in Gillespie's share. That does not prove that particular undecided or Sarvis respondents switched to Gillespie." }, { "status": "unresolved", "text": "No race-specific methodological audit establishing a single cause was verified here. Turnout composition, nonresponse, late choice and allocation remain possibilities rather than findings." }, { "status": "selection caution", "text": "This is one clearly documented final poll, not an industry average or a claim that every poll missed by the same amount." } ], "sources": [ { "label": "PPP original questionnaire/crosstabs, October 29–30, 2014", "url": "https://www.scribd.com/document/245109946/VA-Sen-PPP-for-LCV-Oct-2014", "kind": "primary pollster release", "detail": "937 likely voters, Warner 49, Gillespie 40, Sarvis 5, undecided 6; sponsored by LCV Action Fund." }, { "label": "Virginia Department of Elections, current 2014 Senate results", "url": "https://historical.elections.virginia.gov/contest/44423", "kind": "official state results", "detail": "" }, { "label": "FEC 2014 Senate results, earlier edition", "url": "https://www.fec.gov/documents/1698/2014senate.pdf", "kind": "official federal compilation", "detail": "" } ], "normalizedPollMargin": 10.112359550561798, "normalizedActualMargin": 0.83240710609986, "normalizedSignedError": 9.279952444461939 } ], "counterexample": { "year": 1994, "office": "U.S. House generic ballot", "pollster": "Gallup", "pollDemShare": 46.5, "pollRepShare": 53.5, "pollMargin": -7, "status": "Political shock is not synonymous with polling failure.", "note": "Gallup's final likely-voter estimate favored Republicans 53.5–46.5; it anticipated the direction and approximate size of the 1994 national House wave. Do not put 1994 on a greatest polling-failure list without specifying a different comparator.", "source": "https://news.gallup.com/poll/4147/Tight-Midterm-Congressional-Elections-Hang-Voter-Turnout.aspx" } }