Some Statistical Antics in the Media Arnold Barnett, MIT

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Transcript of Some Statistical Antics in the Media Arnold Barnett, MIT

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Some Statistical Antics in the Media Arnold Barnett, MIT Slide 2 Correlation is Not Always Causality. It Is Sometimes Nothing. Slide 3 Why Music Matters Kids who study music get higher scores on their SATs. Music helps to improve overall academic performance. --Parade Magazine, 12/28/03 Slide 4 "I know from experience that everyone who taught Statistics got a lower (student) evaluation than those who taught courses that are a little less challenging. -- John Antel, Provost, University of Houston (quoted in WSJ 10/23/10) Slide 5 This week, a student sent me an analysis that argued that having a passport reduces the risk of diabetes. Anything wrong with this? Slide 6 Some Comparisons Can Be Intensely Misleading Slide 7 The New York Times Identifies 2003s Top Summer Movies Movie Release Date 1.Finding Nemo May 30 2.The Matrix ReloadedMay 15 3.Pirates of the CaribbeanJuly 9 4.Bruce AlmightyMay 23 5.X2: X-Men UnitedMay 2 The rankings were based on box office receipts, May 2 to August 24, 2003 (!!!!!) Slide 8 Oscar likes films with concise titles --TIME, 2000 TIME based this conclusion on its study of best-picture winners over the previous 20 years. Slide 9 Really? Some Data about Title Lengths TIMEs Winners All US Movies Mean2.3 Words 2.6 words Median2.5 words 2.0 words Slide 10 Some Data Analyses Make Little Sense Slide 11 Will US Do Enough to Identify Potential Terrorists, or Will It Go Too Far? 57% 45% Wont Do Enough Will Go Too Far WhitesBlacks Slide 12 Only once in its 107-year history has the Dow Jones Industrial Average suffered a lower close four years in a row. So ..the odds against it happening this year are something like 104-to-1. ---Barrons, 1/3/03 Slide 13 Of course, the Dow Jones can only decline for a fourth year in a row when it has declined the previous three years. Nest ce pas? Slide 14 That circumstance had only arisen in three years: 1904, 1932, and 1942. In one of these years (namely, 1932) the Dow Jones declined yet again. Proper estimate: 1 in 3? Slide 15 In April 2010, The New York Times informed us of the best places to hail a cab in Manhattan. Its computer analysis of 90 million rides identified the places where the largest numbers of people had started their taxi rides. Slide 16 But the number of people who caught cabs at spot X is not the same as the percentage of people who sought cabs at X and actually got them. And isnt the percentage the appropriate metric for passenger success? Slide 17 Bad Data Can Kill Slide 18 A statistical expert testifying in 2000 for Vice-President Gore stated that the Florida punch-card ballot was defective on its left side. Slide 19 As evidence, he noted a 1998 election in Palm Beach County, in which there were 3% fewer votes recorded in the race for Senator (left side of the ballot) than for Governor (right side). Slide 20 The opposing attorney asked whether the witness had ever examined the 1998 Palm Beach ballot. Had he done so, the lawyer said, he would have realized that the Senate and Governors races were both on the left side of the ballot. Slide 21 Thus, the statisticians left/right comparison was preposterous. (The statistician looked pale.)