Representative Omar’s arithmetic

Women can’t do math. Hypatia of Alexandria and Émilie du Châtelet notwithstanding, this was asserted for thousands of years by men who controlled access to education. With men in charge it was a self-fulfilling prophecy. Women now represent the majority of college students and about 40% of math degrees. That’s progress.

base rateLast week Marcio Rubio caught hell for taking Ilhan Omar’s statement about double standards and unfair terrorism risk assessment out of context. The quoted fragment was: “I would say our country should be more fearful of white men across our country because they are actually causing most of the deaths within this country…”

Most news coverage of the Rubio story (e.g. Vox) note that Omar did not mean that everyone should be afraid of white men as a group, but that, e.g., “violence by right-wing extremists, who are overwhelmingly white and male, really is a bigger problem in the United States today than jihadism.”

Let’s look at the numbers. Wikipedia, following the curious date-range choice of the US GAO, notes: “of the 85 violent extremist incidents that resulted in death since September 12, 2001, far-right politics violent extremist groups were responsible for 62 (73 percent) while radical Islamist violent extremists were responsible for 23 (27 percent).” Note that those are incident counts, not death counts. The fatality counts were 106 (47%) for white extremists and 119 (53%) for jihadists. Counting fatalities instead of incidents reverses the sense of the numbers.

Pushing the terminus post quem back one day adds the 2,977 9-11 fatalities to the category of deaths from jihadists. That makes 3% of fatalities from right wing extremists and 97% from radical Islamist extremists. Pushing the start date further back to 1/1/1990, again using Wikipedia numbers, would include the Oklahoma City bombing (white extremists, 168 dead), nine deaths from jihadists, and 14 other deaths from white wackos, including two radical Christian antisemites and professor Ted Kaczynski. So the numbers since 1990 show 92% of US terrorism deaths from jihadists and 8% from white extremists.

Barring any ridiculous adverse selection of date range (in the 3rd week of April, 1995, 100% of US terrorism deaths involved white extremists), Omar is very, very wrong in her data. The jihadist death toll dwarfs that from white extremists.

But that’s not the most egregious error in her logic – and that of most politicians armed with numbers and a cause. The flagrant abuse of data is what Kahneman and Tversky termed base-rate neglect. Omar, in discussing profiling (sampling a population subset) is arguing about frequencies while citing raw incident counts. The base rate (an informative prior, to Bayesians) is crucial. Even if white extremists caused most – as she claimed – terrorism deaths, there would have to be about one hundred times more deaths from white men (terrorists of all flavors are overwhelmingly male) than from Muslims for her profiling argument to hold. That is, the base rate of being Muslim in the US is about one percent.

The press overwhelmingly worked Rubio over for his vicious smear. 38 of the first 40 Google search results on “Omar Rubio” favored Omar. One favored Rubio and one was an IMDb link to an actor named Omar Rubio. None of the news pieces, including the one friendly to Rubio, mentioned Omar’s bad facts (bad data) or her bad analysis thereof (bad math). Even if she were right about the data – and she is terribly wrong – she’d still be wrong about the statistics.

I disagree with Trump about Omar. She should not go back to Somalia. She should go back to school.

  1. #1 by Matthew Squair on July 28, 2019 - 9:53 pm

    Of course you assume that she was talking in the context of acts of terror committed by ‘white guys’. If however you take her meaning to be white male homicides (without checking the stats) she’d probably be right. So, what did she mean?

    • #2 by Bill Storage on August 1, 2019 - 9:29 pm

      It’s unknowable what she meant; that’s hidden in her mind. But she said that white men (with no qualifier such as supremacist) were a greater danger than are jihadists. As stated it was a patently ignorant claim. As I watch the video, her demeanor seems smug as she delivers it. As Rubio pointed out, and as my quick google search showed, the media overwhelmingly rushed to her defense. Those claims don’t make her less American; but they do make her an ignorant and pompous ass.

  2. #3 by sstorage31 on July 29, 2019 - 4:48 am

    As  Mark Twain said,’ there are lies, damn lies and then statistics.

    • #4 by richard brakeman on July 30, 2019 - 5:08 pm

      Thankfully, the aggregation and analysis of facts and data is my defense from lies, and especially damn lies – a pursuit that seems interminable.

  3. #5 by richard brakeman on July 30, 2019 - 4:56 pm

    Aristotle describes man as rational.

    Rationality presumes that our beliefs are based on evidence (what actually occurred, what was actually said- -even if one weighs the evidence differently from another); and that our actions further our self-interest. Man ordinarily adheres to beliefs even in the absence of or in spite of facts and evidence; and most are readily self-destructive. Egoism? Tribalism? [Other]-ism?

    This situation creates a competitive space for the few that pursue rationality.

  4. #6 by Jams H on August 11, 2019 - 9:48 pm

    Thanks to you I now know that the Unibomber was once a college professor. Fascinating!

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