The Myth of the Super Bowl and Violence Against Women (a slightly-edited Repost)

"Just because you want something to be true, doesn't mean it is true."

-- an old Polish proverb

"Never let empirical data get in the way of a good theory."

-- an even older Polish proverb

No doubt, many of you are aware of the claim that on Super Bowl Sunday violence against women jumps by as much as 40%. This was first noted by a coalition of women’s groups at a news conference a few days before the 1993 Super Bowl and followed up with an article in the Boston Globe a couple of days later.  At about the same time, a psychologist from Denver appeared on “Good Morning America”, claiming that she had gathered 10 years worth of data backing up this claim.

What you may not know is that there are absolutely no data supporting this claim. An investigative reporter from the Washington Post found that the Denver psychologist had never shown her data to anyone (and still hasn’t), and the other studies cited by the women’s groups in the original news conference did not support the claims that they made. Consequently, the Boston Globe retracted the story a few days later. A blow-by-blow account of what happened can be found in Christina Sommers book, (“Who Stole Feminism?") and the citations to the articles, etc. can be found in the book's endnotes. Here are a few pertinent facts:

• January 28, 1993 (Thursday) – News conference called by a coalition of women's groups announcing that anecdotal evidence suggests that Super Bowl Sunday is "the biggest day of the year for violence against women." It was also reported that Old Dominion University had conducted a study that had found that police reports of beatings and hospital admissions in northern Virginia rose 40% after games won by the Redskins during the 1988-1989 season. 
• January 29, 1993 (Friday) – Denver psychologist Lenore Walker claimed on "Good Morning America" to have compiled 10 years worth of data showing a sharp increase in violent incidents against women on Super Bowl Sundays. 
• January 30, 1993 (Saturday) – Article in the Boston Globe reports that women's shelters and hotlines are "flooded with more calls from victims on Super Bowl Sunday than on any other day of the year." She noted that one study of women's shelters in the West showed a 40% increase in calls on Super Bowl Sundays. 
• January 31, 1993 (Super Bowl Sunday) – NBC broadcasts Super Bowl game and makes a special plea for men to remain calm, broadcasting a public service spot reminding men that domestic violence is a crime. CBS and Associated Press called Super Bowl Sunday a "day of dread." 
• January 31, 1993 (Super Bowl Sunday) – While most newspapers and other media outlets took the story at face value, Ken Ringle of the Washington Post actually called around to check on the story's sources and exposed the claims as a myth. He asked Janet Katz, professor of sociology at Old Dominion, who was one of the principal investigators of the study about the connection between violence and football, and she said “That's not what we found at all.” Instead, they found that an increase in emergency room admissions “was not associated with the occurrence of football games in general.”
• January 31, 1993 – Ringle also called the reporter of the Boston Globe article to find out where she got her information. She said she never saw the study but had been told of it by a representative from FAIR (Fairness and Accuracy in Reporting – a media watchdog group that fell down on the job in this case). FAIR then told Ringle that the authority for the 40% figure was Lenore Walker (see above), who in turn referred him to Michael Lindsay, another Denver psychologist, who admitted that he had never seen any data supporting the 40% figure. More to the point, Lenore Walker refused to release the data on which she based her claim, saying she doesn't use data for public consumption.
• January 31, 1993 – Dallas Cowboys defeat the Buffalo Bills 52-17 at Rose Bowl Stadium in Pasadena, CA
• February 2, 1993 – The Boston Globe retracts its January 30th article in a story by Bob Hohler, who quotes several psychologists/counselors who said they didn’t believe the 40% figure when they heard it. He concluded, “Despite their dramatic claims, none of the activists appears to have any evidence that a link actually exists between football and wife-beating.”
• May 1993 – A separate investigation by the American Journalism Review concludes there were no data to support the 40% figure although it did take exception to Ringle’s selective use of quotes out of context.

Why a handful of people thought it necessary to make all this up is a question for another time. For now, enjoy the game (and go Niners!)

LeBron's Alright With Me

I admit that I didn't like the way LeBron James announced he was leaving the Cleveland Cavaliers to join Dwayne Wade and Chris Bosh and play for the Miami Heat ("Miami-Bound LeBron Breaks Hearts in Cleveland"). And I wasn't in the least bit disappointed when the Heat didn't win the NBA Championship the first year after LeBron joined the team.

However, the other night after a Miami Heat fan, Mike Drysch, sank a half-court shot and won $75,000, I changed my mind about LeBron. LeBron ran on to the court, jumped on Mike (good thing Mike wasn't hurt!), and joined in the celebration (see the YouTube video below). It wasn't an act. He was just excited for the guy. How many other professional athletes would have done what LeBron did? I'm guessing few, if any. In know my sample size is small, but LeBron strikes me as a great guy. I think he made a mistake on how he left Cleveland, but in a year in which the sports world seems to be bending over backward to forgive Ray Lewis of his many (and great) sins, surely we can forgive LeBron for his relatively minor (in comparison) shortcomings as well?

The Surprising Decline in Violence

A month or so ago, I offered my two cents about the Sandy Hook school shooting and America's gun culture ("Sandy Hook, Gun Control, and America's Gun Culture"). In that post I also noted that the rate of assault deaths in the US has been declining since the 1970s, and that gun ownership in the US has declined over the same period.

This is not a recent phenomenon. As the cognitive psychologist Steven Pinker has recently argued, violence has been declining, not only in the United States, but around the world for centuries, millennia in fact. He's empirically documented this decline in his recent book, "The Better Angels of Our Nature: Why Violence Has Declined." Unfortunately, it's a very long book, much longer than many people will want to tackle. Luckily, Pinker is a frequent speaker, and one of his TED (Technology, Education and Design) talks is available on YouTube. I highly recommend it. Like all TED talks it is only 20 minutes long, which makes it well worth your time.

Tom Brady, Frank Gore, and NFL Fines

Tom Brady was reportedly fined $10,000 for kicking Baltimore Ravens defender Ed Reed during Sunday's AFC championship game. Before you wax mystical about justice being done, consider the fact that 49er running back Frank Gore was fined $10,500 for wearing his socks too low in Sunday's NFC championship game. No, I am not kidding.

Doctors, Lawyers, and the Rev. Thomas Bayes

Consider the following scenario, which was given to students and staff at Harvard Medical School (reported in "Risk Assessment and Decision Analysis with Bayesian Networks," p. 27):

One person in 1,000 has a prevalence for a particular disease (e.g., breast cancer, HIV). There is a test for detecting this disease, and it is 100% accurate when a person has the disease and 95% accurate for people who don't (in other words, 5% of people who don't have the disease will be incorrectly diagnosed as having the disease -- known as a false-positive). If a randomly selected person tests positive, what is the probability that the person actually has the disease?

Almost half answered 95%, which is almost certainly the most intuitive answer. As you might have already guessed, however, 95% is wrong. In fact, it is horribly wrong. The correct answer is less than 2%. How so, you ask? Because the probability of testing positive and not having the disease is not the same as the probability of having the disease and testing positive.

This can be illustrated relatively simply. To keep things manageable, assume a population of 1,000 people who are given the test. Of these, only one will have the disease, and he or she will test positive. However, approximately 50 (999 * 5%) who don't have the disease will also test positive, which means that 51 out of 1,000 people will test positive for the disease, but only one of those 51 will actually have the disease. So what's the probability that someone who tests positive will actually have the disease? One out of 51 (i.e., 1/51), which equals 1.96%. A far cry from 95%.

Why might this be important? Well, it might help doctors better communicate with their patients. Indeed, something very similar happened to the statistician Leonard Mlodinow ("The Drunkard's Walk: How Randomness Rules Our Lives"). In 1989 he received a call from his doctor who told him that the chances were 999 out of 1,000 he'd be dead within a decade. Why? Because he tested positive for HIV, and at the time the HIV test only produced a false positive 0.1% (i.e., 1/1000) of the time. However, Mlodinow's doctor failed to take into account the underlying probability that only one in 10,000 heterosexual non-IV-abusing white males who got tested were infected with HIV. When this probability is taken into account (as we did above with the Harvard Medical School scenario), the probability that Mlodinow actually had HIV was one in 11 (1/11) or 9.1%, again a far cry from 99.9% that his doctor told him. It isn't hard to imagine that doctors all over the world make similar mistakes and cause their patients undo anxiety.

Doctors aren't the only ones who get probabilities wrong. So do attorneys (and consequently juries), which sometimes leading to convictions (or acquittals) that are wrong. Take, for instance, the following scenario (from Risk Assessment and Decision Analysis with Bayesian Networks," p. 28):

Imagine that a crime has been committed and that the criminal left a trace of blood at the scene. Assume that the blood type is such that only one in every 1,000 people have it, and that a suspect (Fred), who matches the blood type is put on trial. In court, the prosecutor argues that since the chances that an innocent person has the matching blood type is 1 in a 1,000 and Fred has the matching blood type, the chances that Fred is innocent is just 1 in 1,000.

Is the prosecutor right? No. Imagine that there are 10,000 people who could have committed the crime. Of these, one is guilty, but there are approximately 10 others (9,999 * 0.1% = 10) who could have committed the crime. That means the probability that Fred is guilty is one out of eleven (1/11) or 9.1%. Put differently, the probability that Fred is innocent is 90.9%, quite a bit more than the one in one thousand chance the prosecutor argued.

Reasoning such as this is known as the "prosecutor's fallacy" and unfortunately quite common, which means that some people are being imprisoned who shouldn't be and others are being set free who should be locked up. Mlodinow, for instance (p. 118-120) tells the story of the UK's Sally Clark, who had two children die of SIDS (sudden infant death syndrome). After the second one died, she was arrested and charged with smothering her children. An expert witness estimated the odds of having two children dying of SIDS were 73 million to one, and Sally Clark was convicted of murder. As it turned out, the expert was a little off. The real odds were 2.75 million to one, but the problem was that the odds of two children dying of SIDS weren't compared to the odds of two children being murdered by their mother. As it turned out, the British Statistical Society and a mathematician weighed in on the matter and demonstrated that two infants are 9 times more likely to die of SIDS than be murder victims. As a consequence, Sally Clark was eventually set free.

So what does the Rev. Thomas Bayes have to do with all this? Well, the good Reverend was not only a Presbyterian minister, but he was a mathematician interested in probability. More precisely, he was a mathematician interested in the probability of a particular event occurring given what we already know. Without going into great detail, the Rev. Bayes laid the groundwork for what today is known as conditional probability, which I've attempted to illustrate with the examples above. In short, what Bayes was able to show is that we can't know the probability that a positive test for a disease is correct without knowing the underlying probability of someone having the disease. And we can't know if someone who matches the description of someone observed at a crime scene is guilty without knowing the degree to which someone matching their description is present in the population.

Bayes' article on the topic was not published in his lifetime. He left it (and other papers) to another Presbyterian minister, Ronald Price, who was a friend of Benjamin Franklin, Thomas Jefferson, and John Adams. Price edited Bayes' paper and had it published in the proceedings of the British Royal Society (of which Bayes had been a member). Bayes' rule (as it has come to be known) was discovered independently by the Frenchman Pierre Simon Laplace, and it has since been developed and applied in a number of areas. As one author has noted, Bayes' rule helped crack the enigma code during WWII, locate missing subs, show that smoking causes lung cancer, and so on ("The Theory That Would Not Die"). It all seems so simple, but it took a Presbyterian minister to help sort it all out.

The Gospel of Les Mis

The movie, Les Misérables, is all the rage right now, winning 3 Golden Globes and earning 8 Oscar nominations. It's based on the novel by Victor Hugo, which many consider one of the greatest novels of the 19th century. The story begins in 1815 and ends in 1832, at the time of the June Rebellion in Paris. It follows the life of ex-convict Jean Valjean, who after being released from prison (for stealing a loaf of bread), breaks parole in order to create a new life for himself and consequently is pursued mercilessly by Inspector Javert, who knew Valjean when he was a prisoner (in this respect the movie differs somewhat from the book).

One of the novel's (and movie's) themes is how the Gospel is lived out by Valjean and Javert. For Valjean the Gospel's characterized by mercy and forgiveness, largely because of the (largely undeserved) mercy shown to him by an elderly Catholic priest shortly after Valjean release from prison. By contrast, for Javert, the Gospel's characterized by law and judgment, which is why he relentlessly pursues Valjean for his past crimes. Toward the story when Valjean spares Javert's life, Javert discovers that he's unable to turn Valjean over to the authorities. Unable to resolve the conflict between his belief in the law and the mercy shown to him by Valjean, Javert throws himself into the Seine and commits suicide.

The centrality of this theme is interesting because the same debate continues to this day. It appears that for some Christians the Gospel's all about mercy and forgiveness, while for others the Gospel's all about law and judgment. I don't want to suggest that people shouldn't be held responsible for their actions, but a little dose of mercy when dealing with the shortcomings of ourselves and others is surely the better way.

Winston Churchill, Fair Use, and the UK

The third volume of William Manchester's magisterial biography of Winston Churchill (The Last Lion: Defender of the Realm) was released last Fall. Manchester died in 2004, and although he is credited with writing the final volume, most of the writing of the final volume was actually done by Paul Reid. I have yet to read the final volume, but if it's anything like the first two, it will be chock full of quotes from Churchill's speeches, letters, books (he won the Nobel Prize for Literature in 1953), and witty repartees (he could be hilarious). If so, Reid (and I assume Manchester's estate) paid a lot of $s (well, actually £s) to get the rights to include Churchill's words in the book. That's because the UK's fair use laws differ substantially from those in the US. More specifically, in the US, authors can quote the works of other authors for free (up to a certain extent -- you can't quote an entire book, for example), but you can't in the UK, as the author Barry Singer recently discovered when he was in the process of publishing a book on Winston Churchill ("Churchill Style: The Art of Being Winston Churchill"):

"I used 3,872 words of Winston Churchill’s in the book. And that cost me £950, which is roughly 40 cents a word."

The UK's fair use laws don't only apply to Churchill's estate; indeed, it is so restrictive, Sergey Brinand Larry Page, the founders of Google, told Rohan Silva, senior policy advisor to British Prime Minister David Cameron, that they probably wouldn't have been able to start Google in the UK because of how its fair use laws would restrict Google search algorithm.

All of this is the topic of the latest Freakonomics podcast ("Who Owns the Words That Come Out of Your Mouth?"), which as always can be heard at the Freakonomics website or downloaded from iTunes. It is hosted by Stephen Dubner and includes conversations with Barry Singer, Rohan Silva, and  Dubner's co-author Steven Levitt, who (as most of you know) is an economist at U of Chicago. A brief summary of the podcast can be found here: "Who Owns the Words That Come Out of Your Mouth?"