Monday, September 14, 2015

How to Lie With Statistics

I recently saw an article from Mother Jones, a publication not known for its impartiality, titled "A Majority of Cop Killers Have Been White." This comes as no surprise. Setting aside for a moment the predominant whiteness of anti-government, "sovereign citizen" militias and their propensity toward cop-killing, the fact is that most people in the United States are white (presently 77.7%), so even if all races killed cops at an equal rate, a majority of the cop-killers would be white. That's how proportionality works--if you have a majority in an overall group, they will also be the majority of all proportionally represented sub-groups. If you have a pitcher of Kool-Aid made of 99.8% water, then any size cup of that Kool-Aid will also be 99.8% water.

Sub-groups aren't always proportional, though. For example, although 77.7% of people in the United States are white, only 69.8% of all persons arrested in the US in 2013 were white. Studying such disparities can lead us to important insights. The problem is that people pushing their pet political agendas often present the disparities as if they were insights in and of themselves. Such presentations rely on shared assumptions and prejudices. For example, an audience that shares the view that non-white Americans are oppressed victims would see this disparity as prima facie evidence that the American criminal justice system is disproportionally hard on non-whites and easy on whites. An audience that is biased in favor of whites and against non-whites, however, would see the disparity as being proof that whites are more law-abiding, while non-whites are more prone to criminality. When such an assertion is presented to a like-minded audience, it tends to slide by unchallenged and serves only to bolster the audience's confidence in their belief that their prejudices are correct. Psychologists call this phenomenon "confirmation bias."

Notice, for example, that when left-leaning journalists and bloggers speak of the number of persons arrested, convicted, incarcerated, or killed by police, they tend to speak in terms of rates rather than percentages. The reason is that in all of these cases, whites make up the majority, but the majorities are less than proportional. For example, while black Americans make up 13.2% of the population, 23.8% of all people arrested in 2013 were black. So if you want to confirm the bias that black people are treated unfairly, you could present this disparity without further data and interpret it (without supporting evidence) as being proof that the preconceived notion is correct. "Of course black people are treated unfairly! Just look at the numbers!" The unquestioned presumption is that the extra 10.6% of black people arrested didn't deserve to be.

Mother Jones points out that the majority of cop killers are white, and this is true--in 2013, out of 28 known cop killers, 15 of them were white and 11 were black (race was not reported for the other two offenders). Clearly, the majority were white. Bad! Bad, bad white people! But that also means that only about 53.57% of the cop killers were white, while whites are 77.7% of the population overall. On the other hand, about 39.29% of cop killers were black, while blacks are only 13.2% of the population overall. So whites are underrepresented among cop killers, while three times as many blacks are cop killers as would be proportional.

Given the tiny numbers we're talking about, none of this says anything about the relative characters of these races. The character of millions of white and black Americans is not defined by a couple dozen cop killers. But when someone wants to promote one group as good or bad, they'll enhance or diminish the appearance of the numbers regarding that group by shifting to discussion of either percentage or rate, accordingly. When Mother Jones wants to make white people sound worse than black people (as they do), they'll present numbers that show (gasp!) that the majority group commits the majority of a particular type of heinous crime, while glossing over the fact that members of the group they're trying to lift up are more than three times as likely to commit that same crime. I'd presume Fox News would do the same thing in reverse.

In fact, I've seen this done by the other side often enough. When right-wing publications, which see poverty as symptomatic of laziness rather than victimization, want to represent minorities as being lazier than white people, they'll point to the higher rate of blacks receiving food stamps. When left-wingers want to counter those facts, they simply point out that the vast majority of food stamp recipients are white...which tells us nothing, given that whites are in the majority generally.

But even aside from whether we're talking about percentage or rate, there's the issue of assuming what the data implies, as I alluded to on the food stamp issue. Are a higher rate of blacks than whites receiving food stamps because they're lazier, or more likely to be discriminated against in hiring for better-paying jobs, or because their families weren't allowed to accumulate wealth in generations past, or any number of any reasons? It's not evident from the data. But we'll pretend it is, if it seems like the numbers support our conclusions.

As such, you can use data to lie without even changing the type of figure (percentage vs. rate) used. For example, pro-black groups will speak of the higher rate of blacks arrested and convicted. But feminists will point out that the vast majority of people arrested and convicted are men. Bad, bad men! The problem is, these are often the same people. A lefty feminist can believe that more men being arrested is proof that men are inherently more criminal than women, while simultaneously believing that more black people being arrested is proof that the system is racist. We'll move the goal post without even realizing we're doing it. If we used arrest rates as a benchmark of criminal nature, then we'd have to conclude that both men and blacks are more criminal than women and whites, respectively. If we instead use arrest rates as a benchmark of injustice (again, with the implied assumption that the excessive number of arrestees didn't deserve to be arrested), then we must conclude that the system is rigged against both men and blacks. Neither of those views fit neatly into the political boxes as they've been drawn by the two major political parties, however, so people will change the standards from one group to the next as it suits their purposes.

tldr; Data is not analysis. When you hear "most of" or "the majority" or "at a higher rate," look for the rest of the story and carefully study the underlying causes before jumping to any conclusions. If you're seeing the world through any chosen ideology, the facts are probably not always going to support your point of view.

Wednesday, September 2, 2015

A Little Perspective

When a police officer shoots a suspect, it's often the case that the wounded suspect is then handcuffed and left to lie bleeding on the ground without first aid until the scene is secured and an ambulance arrives. If other officers are on the scene at the time of the shooting, multiple officers may fire on the suspect at once, increasing the number of wounds he's likely to sustain. When someone shoots a police officer, that police officer is typically wearing body armor and has been trained in how to survive a gunfight. The officer is normally in radio contact with other officers and/or dispatch, may have other officers assisting him, and normally has an emergency vehicle with lights and siren at his disposal for self-rescue. All of these factors combined mean that an officer who is shot in the line of duty is far, far more likely to survive than is a suspect who's shot by police. The odds are stacked against the suspect's survival and in favor of the officer's survival. Please keep this in mind as you read the following.

Out of a population of 318,900,000 residents, the police have killed 776 so far this year. That means the police have killed 0.24 people per 100,000. That's about one per 416,667 people. Imagine a city or a county with a population of 416,667, where the police kill one criminal a year. That probably wouldn't seem excessive. Newsworthy, but not prima facie evidence of excessive force.

Of those 776 killed, 582 were armed. Black people were killed at a higher rate than whites and hispanics, with about 0.5 per 100,000 black residents being killed by police. That's one black person killed per 200,000, with about a 3-in-4 chance that he was armed at the time.

According to the FBI, the murder rate for the whole country was 4.7 per 100,000 in 2013, the most recent year for which they have data. That means that Americans who aren't cops are being killed by each other 9.4 times as often as they're being killed by police. If seeing a cop makes you worry about being killed, you should worry nine times as much when you see anybody who's not a cop.

As of yesterday, 83 police officers have died in the line of duty this year. 83 is a much smaller number than 776; however, that's out of a total of around 900,000 officers versus 318,900,000 residents. Cops are being killed this year at a rate of 9.22 per 100,000. That's nearly double the murder rate. In other words, despite how much the odds are stacked in favor of a cop surviving a gunfight, Americans are killing their police officers at almost twice the rate that they're killing anyone else, and about eighteen-and-a-half times as often as cops kill black people.

We have all these facts in front of us, and yet the public narrative is that cops are the ones who are violently out of control, and that the biggest thing black people have to worry about is being killed by the police, when there's only a one-in-200,000 chance of that happening, and only one-in-800,000 if they're unarmed. That's a smidge more likely than your chances of being struck by lightning (1-in-960,000). If you listen to left-leaning news commentators, though--or worse, the angry echo chambers that exist in the liberal pockets of the Internet--you'll get the idea that black communities are under siege, where parents have "the talk" with their kids to keep them from being murdered by police, and that even well-meaning police officers of color are unwittingly being driven by their inherent biases to kill black people at the first opportunity that presents itself, like Manchurian Candidates in blue, brainwashed by neo-Nazis to commit a genocide against the black a rate of about ten percent of the normal murder rate.

If, then, people would like to preserve what's left of their credibility, they'd do well to put away their race cards and quit crying "wolf!" every time an aspiring cop killer loses a fight and happens to be black. Is there a problem of excessive use of force by the police in this country? Certainly. One innocent life lost is too many. But when we lose all sense of perspective, when we hysterically elevate this problem to the front and center of social discourse at the expense of greater and more pressing problems like poverty, war, climate change, and growing inequality, we do the entire world an injustice. When people respond to chants of "Black Lives Matter" with "Blue Lives Matter" or retorts about how people should focus on black-on-black violence if they really believe that black lives matter, it's not an attempt to advance racism. It's an attempt to cut through the histrionics, and to order priorities by the actual numbers instead of by how successfully a sensationalist media seeking higher ratings has managed to inflame people's emotions.