karl_lembke (karl_lembke) wrote,


StatGuy, at Magic Statistics, takes a look at an article in the Washington Post. This article purports to show that:
Americans are more willing to provide extended government assistance to white victims of Hurricane Katrina than to African Americans and other minorities — particularly blacks with darker skin.

Overall, the "penalty" for being black and a Katrina victim amounted to about $1,000 . . .

Said StatGuy:
This is a disturbing allegation and, since I’m a professional statistician, I thought I’d take a deeper look at this survey and the findings based thereon.

So what did he find?

Well, first of all, he did not find anything but the barest outline of how the numbers were gathered. Certainly nothing like a full description of the methodology.
However, enough information is found in the two news articles to conclude that the survey is fatally flawed, the results virtually worthless, and the claim of widespread subconscious racism among Americans unsupported.

Were survey respondents drawn at random from the universe of all Americans? No, they were not, for this was an “online” survey.

Further confirmation that survey respondents do not represent the American population is found in the more detailed of the two articles which mentions some of the demographic characteristics of the survey sample.

The allegation that American harbour “subconscious racial bias” arises from the fact that, on average, the 2300 survey respondents were willing to award a hypothetical white Hurricane Katrina victim government assistance of $1501 per month for 12.38 months. However, when the hypothetical victim was African-American, the average award was $1498 per month for 11.64 months. Thus, survey respondents were willing to award a hypothetical white Katrina victim a total of $18,582 and a hypothetical black Katrina victim $17,437. This is the source of the claim cited at the top, “[T]he ‘penalty’ for being black and a Katrina victim amounted to about $1,000”.

StatGuy has problems with this calculation.
Come to think of it, so do I. I'd love to see a copy of the survey. The difference between $1501/month and $1498/month is not that significant. In fact, it's almost certainly noise. The $1000 "penalty" results from the difference in the number of months people voted to give assistance.
I'd love to know what the granularity is in the time dimension. Were respondants allowed to decide how many days to give assistance, or were they limited to an integral number of weeks? Or months?
Maybe 0.74 months is also going to be lost in the noise.
Tags: politics

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