NOTES

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INTRODUCTION

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  2    American voters largely did not care that Barack Obama: Katie Fretland, “Gallup: Race Not Important to Voters,” The Swamp, Chicago Tribune, June 2008.

  2    Berkeley pored through: Alexandre Mas and Enrico Moretti, “Racial Bias in the 2008 Presidential Election,” American Economic Review 99, no. 2 (2009).

  2    post-racial society: On the November 12, 2009, episode of his show, Lou Dobbs said we lived in a “post-partisan, post-racial society.” On the January 27, 2010, episode of his show, Chris Matthews said that President Obama was “post-racial by all appearances.” For other examples, see Michael C. Dawson and Lawrence D. Bobo, “One Year Later and the Myth of a Post-Racial Society,” Du Bois Review: Social Science Research on Race 6, no. 2 (2009).

  5    I analyzed data from the General Social Survey: Details on all these calculations can be found on my website, sethsd.com, in the csv labeled “Sex Data.” Data from the General Social Survey can be found at http://gss.norc.org/.

  5    fewer than 600 million condoms: Data provided to the author.

  7    searches and sign-ups for Stormfront: Author’s analysis of Google Trends data. I also scraped data on all members of Stormfront, as discussed in Seth Stephens-Davidowitz, “The Data of Hate,” New York Times, July 13, 2014, SR4. The relevant data can be downloaded at sethsd.com, in the data section headlined “Stormfront.”

  7    more searches for “nigger president” than “first black president”: Author’s analysis of Google Trends data. The states for which this is true include Kentucky, Louisiana, Arizona, and North Carolina.

  9    rejected by five academic journals: The paper was eventually published as Seth Stephens-Davidowitz, “The Cost of Racial Animus on a Black Candidate: Evidence Using Google Search Data,” Journal of Public Economics 118 (2014). More details about the research can be found there. In addition, the data can be found at my website, sethsd.com, in the data section headlined “Racism.”

 13   single factor that best correlated: “Strongest correlate I’ve found for Trump support is Google searches for the n-word. Others have reported this too” (February 28, 2016, tweet). See also Nate Cohn, “Donald Trump’s Strongest Supporters: A New Kind of Democrat,” New York Times, December 31, 2015, A3.

 13   This shows the percent of Google searches that include the word “nigger(s).” Note that, because the measure is as a percent of Google searches, it is not arbitrarily higher in places with large populations or places that make a lot of searches. Note also that some of the differences in this map and the map for Trump support have obvious explanations. Trump lost popularity in Texas and Arkansas because they were the home states of two of his opponents, Ted Cruz and Mike Huckabee.

 13   This is survey data from Civis Analytics from December 2015. Actual voting data is less useful here, since it is highly influenced by when the primary took place and the voting format. The maps are reprinted with permission from the New York Times.

 15   2.5 million trillion bytes of data: “Bringing Big Data to the Enterprise,” IBM, https://www-01.ibm.com/software/data/bigdata/what-is-big-data.html.

 17   needle comes in an increasingly larger haystack: Nassim M. Taleb, “Beware the Big Errors of ‘Big Data,’ ” Wired, February 8, 2013, http://www.wired.com/2013/02/big-data-means-big-errors-people.

 18   neither racist searches nor membership in Stormfront: I examined how internet racism changed in parts of the country with high and low exposure to the Great Recession. I looked at both Google search rates for “nigger(s)” and Stormfront membership. The relevant data can be downloaded at sethsd.com, in the data sections headlined “Racial Animus” and “Stormfront.”

 18   But Google searches reflecting anxiety: Seth Stephens-Davidowitz, “Fifty States of Anxiety,” New York Times, August 7, 2016, SR2. Note, while the Google searches do give much bigger samples, this pattern is consistent with evidence from surveys. See, for example, William C. Reeves et al., “Mental Illness Surveillance Among Adults in the United States,” Morbidity and Mortality Weekly Report Supplement 60, no. 3 (2011).

 18   search for jokes: This is discussed in Seth Stephens-Davidowitz, “Why Are You Laughing?” New York Times, May 15, 2016, SR9. The relevant data can be downloaded at sethsd.com, in the data section headlined “Jokes.”

 19   “my husband wants me to breastfeed him”: This is discussed in Seth Stephens-Davidowitz, “What Do Pregnant Women Want?” New York Times, May 17, 2014, SR6.

 19   porn searches for depictions of women breastfeeding men: Author’s analysis of PornHub data.

 19   Women make nearly as many: This is discussed in Seth Stephens-Davidowitz, “Searching for Sex,” New York Times, January 25, 2015, SR1.

 20   “poemas para mi esposa embarazada”: Stephens-Davidowitz, “What Do Pregnant Women Want?”

 21   Friedman says: I interviewed Jerry Friedman by phone on October 27, 2015.

 21   sampling of all their data: Hal R. Varian, “Big Data: New Tricks for Econometrics,” Journal of Economic Perspectives 28, no. 2 (2014).

CHAPTER 1: YOUR FAULTY GUT

 26   The best data science, in fact, is surprisingly intuitive: I am speaking about the corner of data analysis I know about—data science that tries to explain and predict human behavior. I am not speaking of artificial intelligence that tries to, say, drive a car. These methodologies, while they do utilize tools discovered from the human brain, are less easy to understand.

 28   what symptoms predict pancreatic cancer: John Paparrizos, Ryan W. White, and Eric Horvitz, “Screening for Pancreatic Adenocarcinoma Using Signals from Web Search Logs: Feasibility Study and Results,” Journal of Oncology Practice (2016).

 31   Winter climate swamped all the rest: This research is discussed in Seth Stephens-Davidowitz, “Dr. Google Will See You Now,” New York Times, August 11, 2013, SR12.

 32   biggest dataset ever assembled on human relationships: Lars Backstrom and Jon Kleinberg, “Romantic Partnerships and the Dispersion of Social Ties: A Network Analysis of Relationship Status on Facebook,” in Proceedings of the 17th ACM Conference on Computer Supported Cooperative Work & Social Computing (2014).

 33   people consistently rank: Daniel Kahneman, Thinking, Fast and Slow (New York: Farrar, Straus and Giroux, 2011).

 33   asthma causes about seventy times more deaths: Between 1979 and 2010, on average, 55.81 Americans died from tornados and 4216.53 Americans died from asthma. See Annual U.S. Killer Tornado Statistics, National Weather Service, http://www.spc.noaa.gov/climo/torn/fatalmap.php and Trends in Asthma Morbidity and Mortality, American Lung Association, Epidemiology and Statistics Unit.

 33   Patrick Ewing: My favorite Ewing videos are “Patrick Ewing’s Top 10 Career Plays,” YouTube video, posted September 18, 2015, https://www.youtube.com/watch?v=Y29gMuYymv8; and “Patrick Ewing Knicks Tribute,” YouTube video, posted May 12, 2006, https://www.youtube.com/watch?v=8T2l5Emzu-I.

 34   “basketball as a matter of life or death”: S. L. Price, “Whatever Happened to the White Athlete?” Sports Illustrated, December 8, 1997.

 34   an internet survey: This was a Google Consumer Survey I conducted on October 22, 2013. I asked, “Where would you guess that the majority of NBA players were born?” The two choices were “poor neighborhoods” and “middle-class neighborhoods”; 59.7 percent of respondents picked “poor neighborhoods.”

 36   a black person’s first name is an indication of his socioeconomic background: Roland G. Fryer Jr. and Steven D. Levitt, “The Causes and Consequences of Distinctively Black Names,” Quarterly Journal of Economics 119, no. 3 (2004).

 37   Among all African-Americans born in the 1980s: Centers for Disease Control and Prevention, “Health, United States, 2009,” Table 9, Nonmarital Childbearing, by Detailed Race and Hispanic Origin of Mother, and Maternal Age: United States, Selected Years 1970–2006.

 37   Chris Bosh . . . Chris Paul: “Not Just a Typical Jock: Miami Heat Forward Chris Bosh’s Interests Go Well Beyond Basketball,” PalmBeachPost.com, February 15, 2011, http://www.palmbeachpost.com/news/sports/basketball/not-just-a-typical-jock-miami-heat-forward-chris-b/nLp7Z/; Dave Walker, “Chris Paul’s Family to Compete on ‘Family Feud,’ nola.com, October 31, 2011, http://www.nola.com/tv/index.ssf/2011/10/chris_pauls_family_to_compete.html.

 38   four inches taller: “Why Are We Getting Taller as a Species?” Scientific American, http://www.scientificamerican.com/article/why-are-we-getting-taller/. Interestingly, Americans have stopped getting taller. Amanda Onion, “Why Have Americans Stopped Growing Taller?” ABC News, July 3, 2016, http://abcnews.go.com/Technology/story?id=98438&page=1. I have argued that one of the reasons there has been a huge increase in foreign-born NBA players is that other countries are catching up to the United States in height. The number of American-born seven-footers in the NBA increased sixteenfold from 1946 to 1980 as Americans grew. It has since leveled off, as Americans have stopped growing. Meanwhile, the number of seven-footers from other countries has risen substantially. The biggest increase in international players, I found, has been extremely tall men from countries, such as Turkey, Spain, and Greece, where there have been noticeable increases in childhood health and adult height in recent years.

 38   Americans from poor backgrounds: Carmen R. Isasi et al., “Association of Childhood Economic Hardship with Adult Height and Adult Adiposity among Hispanics/Latinos: The HCHS/SOL Socio-Cultural Ancillary Study,” PloS One 11, no. 2 (2016); Jane E. Miller and Sanders Korenman, “Poverty and Children’s Nutritional Status in the United States,” American Journal of Epidemiology 140, no. 3 (1994); Harry J. Holzer, Diane Whitmore Schanzenbach, Greg J. Duncan, and Jens Ludwig, “The Economic Costs of Childhood Poverty in the United States,” Journal of Children and Poverty 14, no. 1 (2008).

 38   the average American man is 5’9”: Cheryl D. Fryar, Qiuping Gu, and Cynthia L. Ogden, “Anthropometric Reference Data for Children and Adults: United States, 2007–2010,” Vital and Health Statistics Series 11, no. 252 (2012).

 39   something like one in five reach the NBA: Pablo S. Torre, “Larger Than Real Life,” Sports Illustrated, July 4, 2011.

 39   middle-class, two-parent families: Tim Kautz, James J. Heckman, Ron Diris, Bas Ter Weel, and Lex Borghans, “Fostering and Measuring Skills: Improving Cognitive and Non-Cognitive Skills to Promote Lifetime Success,” National Bureau of Economic Research Working Paper 20749, 2014.

 39   Wrenn jumped the highest: Desmond Conner, “For Wrenn, Sky’s the Limit,” Hartford Courant, October 21, 1999.

 39   But Wrenn: Doug Wrenn’s story is told in Percy Allen, “Former Washington and O’Dea Star Doug Wrenn Finds Tough Times,” Seattle Times, March 29, 2009.

 40   “Doug Wrenn is dead”: Ibid.

 40   Jordan could be a difficult kid: Melissa Isaacson, “Portrait of a Legend,” ESPN.com, September 9, 2009, http://www.espn.com/chicago/columns/story?id=4457017&columnist=isaacson_melissa. A good Jordan biography is Roland Lazenby, Michael Jordan: The Life (Boston: Back Bay Books, 2015).

 40   His father was: Barry Jacobs, “High-Flying Michael Jordan Has North Carolina Cruising Toward Another NCAA Title,” People, March 19, 1984.

 40   Jordan’s life is filled with stories of his family guiding him: Isaacson, “Portrait of a Legend.”

 41   speech upon induction into the Basketball Hall of Fame: Michael Jordan’s Basketball Hall of Fame Enshrinement Speech, YouTube video, posted February 21, 2012, https://www.youtube.com/watch?v=XLzBMGXfK4c. The most interesting aspect of Jordan’s speech is not that he is so effusive about his parents; it is that he still feels the need to point out slights from early in his career. Perhaps a lifelong obsession with slights is necessary to become the greatest basketball player of all time.

 41   LeBron James was interviewed: “I’m LeBron James from Akron, Ohio,” YouTube video, posted June 20, 2013, https://www.youtube.com/watch?v=XceMbPVAggk.

CHAPTER 2: WAS FREUD RIGHT?

 47   a food’s being shaped like a phallus: I coded foods as being shaped as a phallus if they were significantly more long than wide and generally round. I counted cucumbers, corn, carrots, eggplant, squash, and bananas. The data and code can be found at sethsd.com.

 48   errors collected by Microsoft researchers: The dataset can be downloaded at https://www.microsoft.com/en-us/download/details.aspx?id=52418. The researchers asked users of Amazon Mechanical Turk to describe images. They analyzed the keystroke logs and noted any time someone corrected a word. More details can be found in Yukino Baba and Hisami Suzuki, “How Are Spelling Errors Generated and Corrected? A Study of Corrected and Uncorrected Spelling Errors Using Keystroke Logs,” Proceedings of the Fiftieth Annual Meeting of the Association for Computational Linguistics, 2012. The data, code, and a further description of this research can be found at sethsd.com.

 51   Consider all searches of the form “I want to have sex with my”: The full data—warning: graphic—is as follows:

“I WANT TO HAVE SEX WITH . . .”

MONTHLY GOOGLE SEARCHES WITH THIS EXACT PHRASE

my mom

720

my son

590

my sister

590

my cousin

480

my dad

480

my boyfriend

480

my brother

320

my daughter

260

my friend

170

my girlfriend

140

 52   cartoon porn: For example, “porn” is one of the most common words included in Google searches for various extremely popular animated programs, as seen below.

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 52   babysitters: Based on author’s calculations, these are the most popular female occupations in porn searches by men, broken down by the age of men:

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CHAPTER 3: DATA REIMAGINED

 56   algorithms in place: Matthew Leising, “HFT Treasury Trading Hurts Market When News Is Released,” Bloomberg Markets, December 16, 2014; Nathaniel Popper, “The Robots Are Coming for Wall Street,” New York Times Magazine, February 28, 2016, MM56; Richard Finger, “High Frequency Trading: Is It a Dark Force Against Ordinary Human Traders and Investors?” Forbes, September 30, 2013, http://www.forbes.com/sites/richardfinger/2013/09/30/high-frequency-trading-is-it-a-dark-force-against-ordinary-human-traders-and-investors/#50875fc751a6.

 56   Alan Krueger: I interviewed Alan Krueger by phone on May 8, 2015.

 57   important indicators of how fast the flu: The initial paper was Jeremy Ginsberg, Matthew H. Mohebbi, Rajan S. Patel, Lynnette Brammer, Mark S. Smolinski, and Larry Brilliant, “Detecting Influenza Epidemics Using Search Engine Query Data,” Nature 457, no. 7232 (2009). The flaws in the original model were discussed in David Lazer, Ryan Kennedy, Gary King, and Alessandro Vespignani, “The Parable of Google Flu: Traps in Big Data Analysis,” Science 343, no. 6176 (2014). A corrected model is presented in Shihao Yang, Mauricio Santillana, and S. C. Kou, “Accurate Estimation of Influenza Epidemics Using Google Search Data Via ARGO,” Proceedings of the National Academy of Sciences 112, no. 47 (2015).

 58   which searches most closely track housing prices: Seth Stephens-Davidowitz and Hal Varian, “A Hands-on Guide to Google Data,” mimeo, 2015. Also see Marcelle Chauvet, Stuart Gabriel, and Chandler Lutz, “Mortgage Default Risk: New Evidence from Internet Search Queries,” Journal of Urban Economics 96 (2016).

 60   Bill Clinton: Sergey Brin and Larry Page, “The Anatomy of a Large-Scale Hypertextual Web Search Engine,” Seventh International World-Wide Web Conference, April 14–18, 1998, Brisbane, Australia.

 61   porn sites: John Battelle, The Search: How Google and Its Rivals Rewrote the Rules of Business and Transformed Our Culture (New York: Penguin, 2005).

 61   crowdsource the opinions: A good discussion of this can be found in Steven Levy, In the Plex: How Google Thinks, Works, and Shapes Our Lives (New York: Simon & Schuster, 2011).

 64   “Sell your house”: This quote was also included in Joe Drape, “Ahmed Zayat’s Journey: Bankruptcy and Big Bets,” New York Times, June 5, 2015, A1. However, the article incorrectly attributes the quote to Seder. It was actually made by another member of his team.

 65   I first met up with Seder: I interviewed Jeff Seder and Patty Murray in Ocala, Florida, from June 12, 2015, through June 14, 2015.

 66   Roughly one-third: The reasons racehorses fail are rough estimates by Jeff Seder, based on his years in the business.

 66   hundreds of horses die: Supplemental Tables of Equine Injury Database Statistics for Thoroughbreds, http://jockeyclub.com/pdfs/eid_7_year_tables.pdf.

 66   mostly due to broken legs: “Postmortem Examination Program,” California Animal Health and Food Laboratory System, 2013.

 67   Still, more than three-fourths do not win a major race: Avalyn Hunter, “A Case for Full Siblings,” Bloodhorse, April 18, 2014, http://www.bloodhorse.com/horse-racing/articles/115014/a-case-for-full-siblings.

 67   Earvin Johnson III: Melody Chiu, “E. J. Johnson Loses 50 Lbs. Since Undergoing Gastric Sleeve Surgery,” People, October 1, 2014.

 67   LeBron James, whose mom is 5’5”: Eli Saslow, “Lost Stories of LeBron, Part 1,” ESPN.com, October 17, 2013, http://www.espn.com/nba/story/_/id/9825052/how-lebron-james-life-changed-fourth-grade-espn-magazine.

 68   The Green Monkey: See Sherry Ross, “16 Million Dollar Baby,” New York Daily News, March 12, 2006, and Jay Privman, “The Green Monkey, Who Sold for $16M, Retired,” ESPN.com, February 12, 2008, http://www.espn.com/sports/horse/news/story?id=3242341. A video of the auction is available at “$16 Million Horse,” YouTube video, posted November 1, 2008, https://www.youtube.com/watch?v=EyggMC85Zsg.

 71   weakness of Google’s attempt to predict influenza: Sharad Goel, Jake M. Hofman, Sébastien Lahaie, David M. Pennock, and Duncan J. Watts, “Predicting Consumer Behavior with Web Search,” Proceedings of the National Academy of Sciences 107, no. 41 (2010).

 72   Strawberry Pop-Tarts: Constance L. Hays, “What Wal-Mart Knows About Customers’ Habits,” New York Times, November 14, 2004.

 74   “It worked out great”: I interviewed Orley Ashenfelter by phone on October 27, 2016.

 80   studied hundreds of heterosexual speed daters: Daniel A. McFarland, Dan Jurafsky, and Craig Rawlings, “Making the Connection: Social Bonding in Courtship Situations,” American Journal of Sociology 118, no. 6 (2013).

 82   Leonard Cohen once gave his nephew the following advice for wooing women: Jonathan Greenberg, “What I Learned From My Wise Uncle Leonard Cohen,” Huffington Post, November 11, 2016.

 83   the words used in hundreds of thousands of Facebook: H. Andrew Schwartz et al., “Personality, Gender, and Age in the Language of Social Media: The Open-Vocabulary Approach,” PloS One 8, no. 9 (2013). The paper also breaks down the ways people speak based on how they score on personality tests. Here is what they found:

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 88   text of thousands of books and movie scripts: Andrew J. Reagan, Lewis Mitchell, Dilan Kiley, Christopher M. Danforth, and Peter Sheridan Dodds, “The Emotional Arcs of Stories Are Dominated by Six Basic Shapes,” EPJ Data Science 5, no. 1 (2016).

 91   what types of stories get shared: Jonah Berger and Katherine L. Milkman, “What Makes Online Content Viral?” Journal of Marketing Research 49, no. 2 (2012).

 95   why do some publications lean left: This research is all fleshed out in Matthew Gentzkow and Jesse M. Shapiro, “What Drives Media Slant? Evidence from U.S. Daily Newspapers,” Econometrica 78, no. 1 (2010). Although they were merely Ph.D. students when this project started, Gentzkow and Shapiro are now star economists. Gentzkow, now a professor at Stanford, won the 2014 John Bates Clark Medal, given to the top economist under the age of forty. Shapiro, now a professor at Brown, is an editor of the prestigious Journal of Political Economy. Their joint paper on media slant is among the most cited papers for each.

 96   Rupert Murdoch: Murdoch’s ownership of the conservative New York Post could be explained by the fact that New York is so big, it can support newspapers of multiple viewpoints. However, it seems pretty clear the Post consistently loses money. See, for example, Joe Pompeo, “How Much Does the ‘New York Post’ Actually Lose?” Politico, August 30, 2013, http://www.politico.com/media/story/2013/08/how-much-does-the-new-york-post-actually-lose-001176.

 97   Shapiro told me: I interviewed Matt Gentzkow and Jesse Shapiro on August 16, 2015, at the Royal Sonesta Boston.

 98   scanned yearbooks from American high schools: Kate Rakelly, Sarah Sachs, Brian Yin, and Alexei A. Efros, “A Century of Portraits: A Visual Historical Record of American High School Yearbooks,” paper presented at International Conference on Computer Vision, 2015. The photos are reprinted with permission from the authors.

 99   subjects in photos copied subjects in paintings: See, for example, Christina Kotchemidova, “Why We Say ‘Cheese’: Producing the Smile in Snapshot Photography,” Critical Studies in Media Communication 22, no. 1 (2005).

100  measure GDP based on how much light there is in these countries at night: J. Vernon Henderson, Adam Storeygard, and David N. Weil, “Measuring Economic Growth from Outer Space,” American Economic Review 102, no. 2 (2012).

101  estimated GDP was now 90 percent higher: Kathleen Caulderwood, “Nigerian GDP Jumps 89% as Economists Add in Telecoms, Nollywood,” IBTimes, April 7, 2014, http://www.ibtimes.com/nigerian-gdp-jumps-89-economists-add-telecoms-nollywood-1568219.

101  Reisinger said: I interviewed Joe Reisinger by phone on June 10, 2015.

103  $50 million: Leena Rao, “SpaceX and Tesla Backer Just Invested $50 Million in This Startup,” Fortune, September 24, 2015.

CHAPTER 4: DIGITAL TRUTH SERUM

106  important paper in 1950: Hugh J. Parry and Helen M. Crossley, “Validity of Responses to Survey Questions,” Public Opinion Quarterly 14, 1 (1950).

106  survey asked University of Maryland graduates: Frauke Kreuter, Stanley Presser, and Roger Tourangeau, “Social Desirability Bias in CATI, IVR, and Web Surveys,” Public Opinion Quarterly 72(5), 2008.

107  failure of the polls: For an article arguing that lying might be a problem in trying to predict support for Trump, see Thomas B. Edsall, “How Many People Support Trump but Don’t Want to Admit It?” New York Times, May 15, 2016, SR2. But for an argument that this was not a large factor, see Andrew Gelman, “Explanations for That Shocking 2% Shift,” Statistical Modeling, Causal Inference, and Social Science, November 9, 2016, http://andrewgelman.com/2016/11/09/explanations-shocking-2-shift/.

107  says Tourangeau: I interviewed Roger Tourangeau by phone on May 5, 2015.

107  so many people say they are above average: This is discussed in Adam Grant, Originals: How Non-Conformists Move the World (New York: Viking, 2016). The original source is David Dunning, Chip Heath, and Jerry M. Suls, “Flawed Self-Assessment: Implications for Health, Education, and the Workplace,” Psychological Science in the Public Interest 5 (2004).

108  mess with surveys: Anya Kamenetz, “ ‘Mischievous Responders’ Confound Research on Teens,” nprED, May 22, 2014, http://www.npr.org/sections/ed/2014/05/22/313166161/mischievous-responders-confound-research-on-teens. The original research this article discusses is Joseph P. Robinson-Cimpian, “Inaccurate Estimation of Disparities Due to Mischievous Responders,” Educational Researcher 43, no. 4 (2014).

110  search for “porn” more than they search for “weather”: https://www.google.com/trends/explore?date=all&geo=US&q=porn,weather.

110  admit they watch pornography: Amanda Hess, “How Many Women Are Not Admitting to Pew That They Watch Porn?” Slate, October 11, 2013, http://www.slate.com/blogs/xx_factor/2013/10/11/pew_online_viewing_study_percentage_of_women_who_watch_online_porn_is_growing.html.

110  “cock,” “fuck,” and “porn”: Nicholas Diakopoulus, “Sex, Violence, and Autocomplete Algorithms,” Slate, August 2, 2013, http://www.slate.com/articles/technology/future_tense/2013/08/words_banned_from_bing_and_google_s_autocomplete_algorithms.html.

111  3.6 times more likely to tell Google they regret: I estimate, including various phrasings, there are about 1,730 American Google searches every month explicitly saying they regret having children. There are only about 50 expressing a regret not having children. There are about 15.9 million Americans over the age of forty-five who have no children. There are about 152 million Americans who have children. This means, among the eligible population, people with children are about 3.6 times as likely to express a regret on Google than people without children. Obviously, as mentioned in the text but worth emphasizing again, these confessionals to Google are only made by a small, select number of people—presumably those feeling a strong enough regret that they momentarily forget that Google cannot help them here.

113  highest support for gay marriage: These estimates are from Nate Silver, “How Opinion on Same-Sex Marriage Is Changing, and What It Means,” FiveThirtyEight, March 26, 2013, http://fivethirtyeight.blogs.nytimes.com/2013/03/26/how-opinion-on-same-sex-marriage-is-changing-and-what-it-means/?_r=0.

113  About 2.5 percent of male Facebook users who list a gender of interest say they are interested in men: Author’s analysis of Facebook ads data. I do not include Facebook users who list “men and women.” My analysis suggests a non-trivial percent of users who say they are interested in men and women interpret the question as interest in friendship rather than romantic interest.

115  about 5 percent of male porn searches are for gay-male porn: As discussed, Google Trends does not break down searches by gender. Google AdWords breaks down page views for various categories by gender. However, this data is far less precise. To estimate the searches by gender, I first use the search data to get a statewide estimate of the percent of gay porn searches by state. I then normalize this data by the Google AdWords gender data. Another way to get gender-specific data is using PornHub data. However, PornHub could be a highly selected sample, since many gay people might instead use sites focused only on gay porn. PornHub suggests that gay porn use among men is lower than Google searches would suggest. However, it confirms that there is not a strong relationship between tolerance toward homosexuality and male gay porn use. All this data and further notes are available on my website, at sethsd.com, in the section “Sex.”

116  4 percent of them are openly gay on Facebook: Author’s calculation of Facebook ads data: On February 8, 2017, roughly 300 male high school students in San Francisco-Oakland-San Jose media market on Facebook said they were interested in men. Roughly, 7,800 said they were interested in women.

119  “In Iran we don’t have homosexuals”: “ ‘We Don’t Have Any Gays in Iran,’ Iranian President Tells Ivy League Audience,” DailyMail.com, September 25, 2007, http://www.dailymail.co.uk/news/article-483746/We-dont-gays-Iran-Iranian-president-tells-Ivy-League-audience.html.

119  “We do not have them in our city”: Brett Logiurato, “Sochi Mayor Claims There Are No Gay People in the City,” Sports Illustrated, January 27, 2014.

119  internet behavior reveals significant interest in gay porn in Sochi and Iran: According to Google AdWords, there are tens of thousands of searches every year for “гей порно” (gay porn). The percent of porn searches for gay porn is roughly similar in Sochi as in the United States. Google AdWords does not include data for Iran. PornHub also does not report data for Iran. However, PornMD studied their search data and reported that five of the top ten search terms in Iran were for gay porn. This included “daddy love” and “hotel businessman” and is reported in Joseph Patrick McCormick, “Survey Reveals Searches for Gay Porn Are Top in Countries Banning Homosexuality,” PinkNews, http://www.pinknews.co.uk/2013/03/13/survey-reveals-searches-for-gay-porn-are-top-in-countries-banning-homosexuality/. According to Google Trends, about 2 percent of porn searches in Iran are for gay porn, which is lower than in the United States but still suggests widespread interest.

122  When it comes to sex: Stephens-Davidowitz, “Searching for Sex.” Data for this section can be found on my website, sethsd.com, in the section “Sex.”

122  11 percent of women: Current Contraceptive Status Among Women Aged 15–44: United States, 2011–2013, Centers for Disease Control and Prevention, http://www.cdc.gov/nchs/data/databriefs/db173_table.pdf#1.

122  10 percent of them to become pregnant every month: David Spiegelhalter, “Sex: What Are the Chances?” BBC News, March 15, 2012, http://www.bbc.com/future/story/20120313-sex-in-the-city-or-elsewhere.

122  1 in 113 women of childbearing age: There are roughly 6.6 million pregnancies every year and there are 62 million women between ages 15 and 44.

128  performing oral sex on the opposite gender: As mentioned, I do not know the gender of a Google searcher. I am assuming that the overwhelming majority of searches looking how to perform cunnilingus are by men and that the overwhelming majority of searches looking how to perform fellatio are by women. This is both because the large majority of people are straight and because there might be less of a need to learn how to please a same-sex partner.

128  top five negative words: Author’s analysis of Google AdWords data.

130  kill them: Evan Soltas and Seth Stephens-Davidowitz, “The Rise of Hate Search,” New York Times, December 13, 2015, SR1. Data and more details can be found on my website, sethsd.com, in the section “Islamophobia.”

132  seventeen times more common: Author’s analysis of Google Trends data.

132  Martin Luther King Jr. Day: Author’s analysis of Google Trends data.

133  correlates with the black-white wage gap: Ashwin Rode and Anand J. Shukla, “Prejudicial Attitudes and Labor Market Outcomes,” mimeo, 2013.

134  Their parents: Seth Stephens-Davidowitz, “Google, Tell Me. Is My Son a Genius?” New York Times, January 19, 2014, SR6. The data for exact searches can be found using Google AdWords. Estimates can also be found with Google Trends, by comparing searches with the words “gifted” and “son” versus “gifted” and “daughter.” Compare, for example, https://www.google.com/trends/explore?date=all&geo=US&q=gifted%20son,gifted%20daughter and https://www.google.com/trends/explore?date=all&geo=US&q=overweight%20son,overweight%20daughter. One exception to the general pattern that there are more questions about sons’ brains and daughters’ bodies is there are more searches for “fat son” than “fat daughter.” This seems to be related to the popularity of incest porn discussed earlier. Roughly 20 percent of searches with the words “fat” and “son” also include the word “porn.”

135  girls are 9 percent more likely than boys to be in gifted programs: “Gender Equity in Education: A Data Snapshot,” Office for Civil Rights, U.S. Department of Education, June 2012, http://www2.ed.gov/about/offices/list/ocr/docs/gender-equity-in-education.pdf.

136  About 28 percent of girls are overweight, while 35 percent of boys are: Data Resource Center for Child and Adolescent Health, http://www.childhealthdata.org/browse/survey/results?q=2415&g=455&a=3879&r=1.

137  Stormfront profiles: Stephens-Davidowitz, “The Data of Hate.” The relevant data can be downloaded at sethsd.com, in the data section headlined “Stormfront.”

139  Stormfront during Donald Trump’s candidacy: Google search interest in Stormfront was similar in October 2016 to the levels it was during October 2015. This is in stark contrast to the situation during Obama’s first election. In October 2008, search interest in Stormfront had risen almost 60 percent compared to the previous October. On the day after Obama was elected, Google searches for Stormfront had risen roughly tenfold. On the day after Trump was elected, Stormfront searches rose about two-point-five-fold. This was roughly equivalent to the rise the day after George W. Bush was elected in 2004 and may largely reflect news interest among political junkies.

141  political segregation on the internet: Matthew Gentzkow and Jesse M. Shapiro, “Ideological Segregation Online and Offline,” Quarterly Journal of Economics 126, no. 4 (2011).

144  friends on Facebook: Eytan Bakshy, Solomon Messing, and Lada A. Adamic, “Exposure to Ideologically Diverse News and Opinion on Facebook,” Science 348, no. 6239 (2015). They found that, among the 9 percent of active Facebook users who declare their ideology, about 23 percent of their friends who also declare an ideology have the opposite ideology and 28.5 percent of the news they see on Facebook is from the opposite ideology. These numbers are not directly comparable with other numbers on segregation because they only include the small sample of Facebook users who declare their ideology. Presumably, these users are much more likely to be politically active and associate with other politically active users with the same ideology. If this is correct, the diversity among all users will be much greater.

144  one crucial reason that Facebook: Another factor that makes social media surprisingly diverse is that it gives a big bonus to extremely popular and widely shared articles, no matter their political slant. See Solomon Messing and Sean Westwood, “Selective Exposure in the Age of Social Media: Endorsements Trump Partisan Source Affiliation When Selecting News Online,” 2014.

144  more friends on Facebook than they do offline: See Ben Quinn, “Social Network Users Have Twice as Many Friends Online as in Real Life,” Guardian, May 8, 2011. This article discusses a 2011 study by the Cystic Fibrosis Trust, which found that the average social network user has 121 online friends compared with 55 physical friends. According to a 2014 Pew Research study, the average Facebook user had more than 300 friends. See Aaron Smith, “6 New Facts About Facebook,” February 3, 2014, http://www.pewresearch.org/fact-tank/2014/02/03/6-new-facts-about-facebook/.

144  weak ties: Eytan Bakshy, Itamar Rosenn, Cameron Marlow, and Lada Adamic, “The Role of Social Networks in Information Diffusion,” Proceedings of the 21st International Conference on World Wide Web, 2012.

145  “doom-and-gloom predictions haven’t come true”: “Study: Child Abuse on Decline in U.S.,” Associated Press, December 12, 2011.

146  did child abuse really drop: See Seth Stephens-Davidowitz, “How Googling Unmasks Child Abuse,” New York Times, July 14, 2013, SR5, and Seth Stephens-Davidowitz, “Unreported Victims of an Economic Downturn,” mimeo, 2013.

146  facing long wait times and giving up: “Stopping Child Abuse: It Begins With You,” The Arizona Republic, March 26, 2016.

147  off-the-books ways to terminate a pregnancy: Seth Stephens-Davidowitz, “The Return of the D.I.Y. Abortion,” New York Times, March 6, 2016, SR2. Data and more details can be found on my website, sethsd.com, in the section “Self-Induced Abortion.”

150  similar average circulations: Alliance for Audited Media, Consumer Magazines, http://abcas3.auditedmedia.com/ecirc/magtitlesearch.asp.

151  On Facebook: Author’s calculations, on October 4, 2016, using Facebook’s Ads Manager.

151  top ten most visited websites: “List of Most Popular Websites,” Wikipedia. According to Alexa, which tracks browsing behavior, as of September 4, 2016, the most popular porn site was XVideos, and this was the 57th-most-popular website. According to SimilarWeb, as of September 4, 2016, the most popular porn site was XVideos, and this was the 17th-most-popular website. The top ten, according to Alexa, are Google, YouTube, Facebook, Baidu, Yahoo!, Amazon, Wikipedia, Tencent QQ, Google India, and Twitter.

153  In the early morning of September 5, 2006: This story is from David Kirkpatrick, The Facebook Effect: The Inside Story of the Company That Is Connecting the World (New York: Simon & Schuster, 2010).

155  great businesses are built on secrets: Peter Thiel and Blake Masters, Zero to One: Notes on Startups, or How to Build the Future (New York: The Crown Publishing Group, 2014).

157  says Xavier Amatriain: I interviewed Xavier Amatriain by phone on May 5, 2015.

159  top questions Americans had during Obama’s 2014: Author’s analysis of Google Trends data.

162  this time at a mosque: “The President Speaks at the Islamic Society of Baltimore,” YouTube video, posted February 3, 2016, https://www.youtube.com/watch?v=LRRVdVqAjdw.

163  hateful, rageful searches against Muslims dropped in the hours after the president’s address: Author’s analysis of Google Trends data. Searches for “kill Muslims” were lower than the comparable period a week before. In addition, searches that included “Muslims” and one of the top five negative words about this group were lower.

CHAPTER 5: ZOOMING IN

166  how childhood experiences influence which baseball team you support: Seth Stephens-Davidowitz, “They Hook You When You’re Young,” New York Times, April 20, 2014, SR5. Data and code for this study can be found on my website, sethsd.com, in the section “Baseball.”

170  the single most important year: Yair Ghitza and Andrew Gelman, “The Great Society, Reagan’s Revolution, and Generations of Presidential Voting,” unpublished manuscript.

173  Chetty explains: I interviewed Raj Chetty by phone on July 30, 2015.

176  escape the grim reaper: Raj Chetty et al., “The Association Between Income and Life Expectancy in the United States, 2001–2014,” JAMA 315, no. 16 (2016).

178  Contagious behavior may be driving some of this: Julia Belluz, “Income Inequality Is Chipping Away at Americans’ Life Expectancy,” vox.com, April 11, 2016.

178  why some people cheat on their taxes: Raj Chetty, John Friedman, and Emmanuel Saez, “Using Differences in Knowledge Across Neighborhoods to Uncover the Impacts of the EITC on Earnings,” American Economic Review 103, no. 7 (2013).

180  I decided to download Wikipedia: This is from Seth Stephens-Davidowitz, “The Geography of Fame,” New York Times, March 23, 2014, SR6. Data can be found on my website, sethsd.com, in the section “Wikipedia Birth Rate, by County.” For help downloading and coding county of birth of every Wikipedia entrant, I thank Noah Stephens-Davidowitz.

183  a big city: For more evidence on the value of cities, see Ed Glaeser, Triumph of the City (New York: Penguin, 2011). (Glaeser was my advisor in graduate school.)

191  many examples of real life imitating art: David Levinson, ed., Encyclopedia of Crime and Punishment (Thousand Oaks, CA: SAGE, 2002).

191  subjects exposed to a violent film will report more anger and hostility: Craig Anderson et al., “The Influence of Media Violence on Youth,” Psychological Science in the Public Interest 4 (2003).

192  On weekends with a popular violent movie: Gordon Dahl and Stefano DellaVigna, “Does Movie Violence Increase Violent Crime?” Quarterly Journal of Economics 124, no. 2 (2009).

195  Google searches can also be broken down by the minute: Seth Stephens-Davidowitz, “Days of Our Digital Lives,” New York Times, July 5, 2015, SR4.

196  alcohol is a major contributor to crime: Anna Richardson and Tracey Budd, “Young Adults, Alcohol, Crime and Disorder,” Criminal Behaviour and Mental Health 13, no. 1 (2003); Richard A. Scribner, David P. MacKinnon, and James H. Dwyer, “The Risk of Assaultive Violence and Alcohol Availability in Los Angeles County,” American Journal of Public Health 85, no. 3 (1995); Dennis M. Gorman, Paul W. Speer, Paul J. Gruenewald, and Erich W. Labouvie, “Spatial Dynamics of Alcohol Availability, Neighborhood Structure and Violent Crime,” Journal of Studies on Alcohol 62, no. 5 (2001); Tony H. Grubesic, William Alex Pridemore, Dominique A. Williams, and Loni Philip-Tabb, “Alcohol Outlet Density and Violence: The Role of Risky Retailers and Alcohol-Related Expenditures,” Alcohol and Alcoholism 48, no. 5 (2013).

196  letting all four of his sons play football: “Ed McCaffrey Knew Christian McCaffrey Would Be Good from the Start—’The Herd,’ ” YouTube video, posted December 3, 2015, https://www.youtube.com/watch?v=boHMmp7DpX0.

197  analyzing piles of data: Researchers have found more from utilizing this crime data broken down into small time increments. One example? Domestic violence complaints rise immediately after a city’s football team loses a game it was expected to win. See David Card and Gordon B. Dahl, “Family Violence and Football: The Effect of Unexpected Emotional Cues on Violent Behavior,” Quarterly Journal of Economics 126, no. 1 (2011).

197  Here’s how Bill Simmons: Bill Simmons, “It’s Hard to Say Goodbye to David Ortiz,” ESPN.com, June 2, 2009, http://www.espn.com/espnmag/story?id=4223584.

198  how can we predict how a baseball player will perform in the future: This is discussed in Nate Silver, The Signal and the Noise: Why So Many Predictions Fail—But Some Don’t (New York: Penguin, 2012).

199  “beefy sluggers” indeed do, on average, peak early: Ryan Campbell, “How Will Prince Fielder Age?” October 28, 2011, http://www.fangraphs.com/blogs/how-will-prince-fielder-age/.

199  Ortiz’s doppelgangers’: This data was kindly provided to me by Rob McQuown of Baseball Prospectus.

204  Kohane asks: I interviewed Isaac Kohane by phone on June 15, 2015.

205  James Heywood is an entrepreneur: I interviewed James Heywood by phone on August 17, 2015.

CHAPTER 6: ALL THE WORLD’S A LAB

207  February 27, 2000: This story is discussed, among other places, in Brian Christian, “The A/B Test: Inside the Technology That’s Changing the Rules of Business,” Wired, April 25, 2012, http://www.wired.com/2012/04/ff_abtesting/.

209  When teachers were paid, teacher absenteeism dropped: Esther Duflo, Rema Hanna, and Stephen P. Ryan, “Incentives Work: Getting Teachers to Come to School,” American Economic Review 102, no. 4 (2012).

209  when Bill Gates learned of Duflo’s work: Ian Parker, “The Poverty Lab,” New Yorker, May 17, 2010.

211  Google engineers ran seven thousand A/B tests: Christian, “The A/B Test.”

211  forty-one marginally different shades of blue: Douglas Bowman, “Goodbye, Google,” stopdesign, March 20, 2009, http://stopdesign.com/archive/2009/03/20/goodbye-google.html.

211  Facebook now runs: Eytan Bakshy, “Big Experiments: Big Data’s Friend for Making Decisions,” April 3, 2014, https://www.facebook.com/notes/facebook-data-science/big-experiments-big-datas-friend-for-making-decisions/10152160441298859/. Sources for information on pharmaceutical studies can be found at “How many clinical trials are started each year?” Quora post, https://www.quora.com/How-many-clinical-trials-are-started-each-year.

211  Optimizely: I interviewed Dan Siroker by phone on April 29, 2015.

214  netting the campaign roughly $60 million: Dan Siroker, “How Obama Raised $60 Million by Running a Simple Experiment,” Optimizely blog, November 29, 2010, https://blog.optimizely.com/2010/11/29/how-obama-raised-60-million-by-running-a-simple-experiment/.

214  The Boston Globe A/B-tests headlines: The Boston Globe A/B tests and results were provided to the author. Some details about the Globe’s testing can be found at “The Boston Globe: Discovering and Optimizing a Value Proposition for Content,” Marketing Sherpa Video Archive, https://www.marketingsherpa.com/video/boston-globe-optimization-summit2. This includes a recorded conversation between Peter Doucette of the Globe and Pamela Markey at MECLABS.

217  Benson says: I interviewed Clark Benson by phone on July 23, 2015.

217  added a rightward-pointing arrow surrounded by a square: “Enhancing Text Ads on the Google Display Network,” Inside AdSense, December 3, 2012, https://adsense.googleblog.com/2012/12/enhancing-text-ads-on-google-display.html.

218  Google customers were critical: See, for example, “Large arrows appearing in google ads—please remove,” DoubleClick Publisher Help Forum, https://productforums.google.com/forum/#!topic/dfp/p_TRMqWUF9s.

219  the rise of behavioral addictions in contemporary society: Adam Alter, Irresistible: The Rise of Addictive Technology and the Business of Keeping Us Hooked (New York: Penguin, 2017).

219  Top addictions reported to Google: Author’s analysis of Google Trends data.

222  says Levitt in a lecture: This is discussed in a video currently featured on the Freakonomics page of the Harry Walker Speakers Bureau, http://www.harrywalker.com/speakers/authors-of-freakonomics/.

225  beer and soft drink ads run during the Super Bowl: Wesley R. Hartmann and Daniel Klapper, “Super Bowl Ads,” unpublished manuscript, 2014.

226  a pimply kid in his underwear: For the strong case that we likely are living in a computer simulation, see Nick Bostrom, “Are We Living in a Computer Simulation?” Philosophical Quarterly 53, no. 211 (2003).

227  Of forty-three American presidents: Los Angeles Times staff, “U.S. Presidential Assassinations and Attempts,” Los Angeles Times, January 22, 2012, http://timelines.latimes.com/us-presidential-assassinations-and-attempts/.

227  Compare John F. Kennedy and Ronald Reagan: Benjamin F. Jones and Benjamin A. Olken, “Do Assassins Really Change History?” New York Times, April 12, 2015, SR12.

227  Kadyrov died: A disturbing video of the attack can be seen at “Parade surprise (Chechnya 2004),” YouTube video, posted March 31, 2009, https://www.youtube.com/watch?v=fHWhs5QkfuY.

227  Hitler had changed his schedule: This story is also discussed in Jones and Olken, “Do Assassins Really Change History?”

228  the effect of having your leader murdered: Benjamin F. Jones and Benjamin A. Olken, “Hit or Miss? The Effect of Assassinations on Institutions and War,” American Economic Journal: Macroeconomics 1, no. 2 (2009).

229  winning the lottery does not: This point is made in John Tierney, “How to Win the Lottery (Happily),” New York Times, May 27, 2014, D5. Tierney’s piece discusses the following studies: Bénédicte Apouey and Andrew E. Clark, “Winning Big but Feeling No Better? The Effect of Lottery Prizes on Physical and Mental Health,” Health Economics 24, no. 5 (2015); Jonathan Gardner and Andrew J. Oswald, “Money and Mental Wellbeing: A Longitudinal Study of Medium-Sized Lottery Wins,” Journal of Health Economics 26, no. 1 (2007); and Anna Hedenus, “At the End of the Rainbow: Post-Winning Life Among Swedish Lottery Winners,” unpublished manuscript, 2011. Tierney’s piece also points out that the famous 1978 study—Philip Brickman, Dan Coates, and Ronnie Janoff-Bulman, “Lottery Winners and Accident Victims: Is Happiness Relative?” Journal of Personality and Social Psychology 36, no. 8 (1978)—which found that winning the lottery does not make you happy was based on a tiny sample.

229  your neighbor winning the lottery: See Peter Kuhn, Peter Kooreman, Adriaan Soetevent, and Arie Kapteyn, “The Effects of Lottery Prizes on Winners and Their Neighbors: Evidence from the Dutch Postcode Lottery,” American Economic Review 101, no. 5 (2011), and Sumit Agarwal, Vyacheslav Mikhed, and Barry Scholnick, “Does Inequality Cause Financial Distress? Evidence from Lottery Winners and Neighboring Bankruptcies,” working paper, 2016.

229  neighbors of lottery winners: Agarwal, Mikhed, and Scholnick, “Does Inequality Cause Financial Distress?”

230  doctors can be motivated by monetary incentives: Jeffrey Clemens and Joshua D. Gottlieb, “Do Physicians’ Financial Incentives Affect Medical Treatment and Patient Health?” American Economic Review 104, no. 4 (2014). Note that these results do not mean that doctors are evil. In fact, the results might be more troubling if the extra procedures doctors ordered when they were paid more to order them actually saved lives. If this were the case, it would mean that doctors needed to be paid enough to order lifesaving treatments. Clemens and Gottlieb’s results suggest, instead, that doctors will order lifesaving treatments no matter how much money they are given to order them. For procedures that don’t help all that much, doctors must be paid enough to order them. Another way to say this: doctors don’t pay too much attention to monetary incentives for life-threatening stuff; they pay a ton of attention to monetary incentives for unimportant stuff.

231  $150 million: Robert D. McFadden and Eben Shapiro, “Finally, a Face to Fit Stuyvesant: A High School of High Achievers Gets a High-Priced Home,” New York Times, September 8, 1992.

231  It offers: Course offerings are available on Stuy’s website, http://stuy.enschool.org/index.jsp.

231  one-quarter of its graduates are accepted: Anna Bahr, “When the College Admissions Battle Starts at Age 3,” New York Times, July 29, 2014, http://www.nytimes.com/2014/07/30/upshot/when-the-college-admissions-battle-starts-at-age-3.html.

231  Stuyvesant trained: Sewell Chan, “The Obama Team’s New York Ties,” New York Times, November 25, 2008; Evan T. R. Rosenman, “Class of 1984: Lisa Randall,” Harvard Crimson, June 2, 2009; “Gary Shteyngart on Stuyvesant High School: My New York,” YouTube video, posted August 4, 2010, https://www.youtube.com/watch?v=NQ_phGkC-Tk; Candace Amos, “30 Stars Who Attended NYC Public Schools,” New York Daily News, May 29, 2015.

231  Its commencement speakers have included: Carl Campanile, “Kids Stuy High Over Bubba: He’ll Address Ground Zero School’s Graduation,” New York Post, March 22, 2002; United Nations Press Release, “Stuyvesant High School’s ‘Multicultural Tapestry’ Eloquent Response to Hatred, Says Secretary-General in Graduation Address,” June 23, 2004; “Conan O’Brien’s Speech at Stuyvesant’s Class of 2006 Graduation in Lincoln Center,” YouTube video, posted May 6, 2012, https://www.youtube.com/watch?v=zAMkUE9Oxnc.

231  Stuy ranked number one: See https://k12.niche.com/rankings/public-high-schools/best-overall/.

232  Fewer than 5 percent: Pamela Wheaton, “8th-Graders Get High School Admissions Results,” Insideschools, March 4, 2016, http://insideschools.org/blog/item/1001064-8th-graders-get-high-school-admissions-results.

235  prisoners assigned to harsher conditions: M. Keith Chen and Jesse M. Shapiro, “Do Harsher Prison Conditions Reduce Recidivism? A Discontinuity-Based Approach,” American Law and Economics Review 9, no. 1 (2007).

236  The effects of Stuyvesant High School? Atila Abdulkadiroğlu, Joshua Angrist, and Parag Pathak, “The Elite Illusion: Achievement Effects at Boston and New York Exam Schools,” Econometrica 82, no. 1 (2014). The same null result was independently found by Will Dobbie and Roland G. Fryer Jr., “The Impact of Attending a School with High-Achieving Peers: Evidence from the New York City Exam Schools,” American Economic Journal: Applied Economics 6, no. 3 (2014).

238  average graduate of Harvard makes: See http://www.payscale.com/college-salary-report/bachelors.

238  similar students accepted to similarly prestigious schools who choose to attend different schools end up in about the same place: Stacy Berg Dale and Alan B. Krueger, “Estimating the Payoff to Attending a More Selective College: An Application of Selection on Observables and Unobservables,” Quarterly Journal of Economics 117, no. 4 (2002).

239  Warren Buffett: Alice Schroeder, The Snowball: Warren Buffett and the Business of Life (New York: Bantam, 2008).

CHAPTER 7: BIG DATA, BIG SCHMATA? WHAT IT CANNOT DO

247  claimed they could predict which way: Johan Bollen, Huina Mao, and Xiaojun Zeng, “Twitter Mood Predicts the Stock Market,” Journal of Computational Science 2, no. 1 (2011).

248  The tweet-based hedge fund was shut down: James Mackintosh, “Hedge Fund That Traded Based on Social Media Signals Didn’t Work Out,” Financial Times, May 25, 2012.

250  could not reproduce the correlation: Christopher F. Chabris et al., “Most Reported Genetic Associations with General Intelligence Are Probably False Positives,” Psychological Science (2012).

252  Zoë Chance: This story is discussed in TEDx Talks, “How to Make a Behavior Addictive: Zoë Chance at TEDx Mill River,” YouTube video, posted May 14, 2013, https://www.youtube.com/watch?v=AHfiKav9fcQ. Some details of the story, such as the color of the pedometer, were fleshed out in interviews. I interviewed Chance by phone on April 20, 2015, and by email on July 11, 2016, and September 8, 2016.

253  Numbers can be seductive: This section is from Alex Peysakhovich and Seth Stephens-Davidowitz, “How Not to Drown in Numbers,” New York Times, May 3, 2015, SR6.

254  cheated outright in administering those tests: Brian A. Jacob and Steven D. Levitt, “Rotten Apples: An Investigation of the Prevalence and Predictors of Teacher Cheating,” Quarterly Journal of Economics 118, no. 3 (2003).

255  says Thomas Kane: I interviewed Thomas Kane by phone on April 22, 2015.

256  “Each measure adds something of value”: Bill and Melinda Gates Foundation, “Ensuring Fair and Reliable Measures of Effective Teaching,” http://k12education.gatesfoundation.org/wp-content/uploads/2015/05/MET_Ensuring_Fair_and_Reliable_Measures_Practitioner_Brief.pdf.

CHAPTER 8: MO DATA, MO PROBLEMS? WHAT WE SHOULDN’T DO

257  Recently, three economists: Oded Netzer, Alain Lemaire, and Michal Herzenstein, “When Words Sweat: Identifying Signals for Loan Default in the Text of Loan Applications,” 2016.

258  about 13 percent of borrowers: Peter Renton, “Another Analysis of Default Rates at Lending Club and Prosper,” October 25, 2012, http://www.lendacademy.com/lending-club-prosper-default-rates/.

261  Facebook likes are frequently correlated: Michal Kosinski, David Stillwell, and Thore Graepel, “Private Traits and Attributes Are Predictable from Digital Records of Human Behavior,” PNAS 110, no. 15 (2013).

265  businesses are at the mercy of Yelp reviews: Michael Luca, “Reviews, Reputation, and Revenue: The Case of Yelp,” unpublished manuscript, 2011.

266  Google searches related to suicide: Christine Ma-Kellams, Flora Or, Ji Hyun Baek, and Ichiro Kawachi, “Rethinking Suicide Surveillance: Google Search Data and Self-Reported Suicidality Differentially Estimate Completed Suicide Risk,” Clinical Psychological Science 4, no. 3 (2016).

267  3.5 million Google searches: This uses a methodology discussed on my website in the notes on self-induced abortion. I compare searches in the Google category “suicide” to searches for “how to tie a tie.” There were 6.6 million Google searches for “how to tie a tie” in 2015. There were 6.5 times more searches in the category suicide. 6.5*6.6/12 » 3.5.

268  12 murders of Muslims reported as hate crimes: Bridge Initiative Team, “When Islamophobia Turns Violent: The 2016 U.S. Presidential Election,” May 2, 2016, available at http://bridge.georgetown.edu/when-islamophobia-turns-violent-the-2016-u-s-presidential-elections/.

CONCLUSION

272  What motivated Popper’s crusade?: Karl Popper, Conjectures and Refutations (London: Routledge & Kegan Paul, 1963).

275  mapped every cholera case in the city: Simon Rogers, “John Snow’s Data Journalism: The Cholera Map That Changed the World,” Guardian, March 15, 2013.

276  Benjamin F. Jones: I interviewed Benjamin Jones by phone on June 1, 2015. This work is also discussed in Aaron Chatterji and Benjamin Jones, “Harnessing Technology to Improve K–12 Education,” Hamilton Project Discussion Paper, 2012.

283  people tend not to finish treatises by economists: Jordan Ellenberg, “The Summer’s Most Unread Book Is . . . ,” Wall Street Journal, July 3, 2014.