Figures Don’t Lie, But Liars Figure

The expression “Figures don’t lie, but liars figure” is a pretty common one among statisticians. If you have pre-determined what you want the output to be, then you can often find a way to manipulate the figures to agree with that pre-determined result.

That is the case with a recent posting that I saw on Facebook that is trying to show that the issues behind Black Lives Matter is a made-up issue. Here is the chart that has been posted.

[Facebook chart]

The individual who made up this chart was at least honest in that he/she showed the source of the data and noted that it had been normalized to death rate per million people. But that’s where the honesty ended as the individual is clearly trying to make a point that “Blacks killed by Whites” is an insignificant figure.

I decided that I needed to look up the figures behind the chart to see what was going on. Here are the original figures from the FBI database. Note that these are from 2013 (apparently the most recent year for which the figures have been compiled and released) and they are part of an overall spreadsheet showing the number of murders committed in that  year by one person killing one person (i.e. eliminating any mass shootings, etc.). There are other columns and rows which have further breakouts by age, gender, etc. but the ones in the top left boxes are the ones that were used as the basis for the Facebook posting.

[FBI data]

I was able to find one analysis by someone else, but it is a lot of text and no graphics (*1). But here is my graphical analysis of what is going on here:

[Excel chart]

The individual “normalized” the raw numbers by converting them to murders per million people using the race of the perpetrator as the divisor (as shown in the yellow boxes). The figure of 245.4 million whites and 41.62 million blacks were used – I don’t know the source of these figures, but they seem relatively correct and I’ll not debate them here.

But it in the choice of using the race of the perpetrator that skews the results, since there are so many more whites than blacks that the former are divided by larger numbers and thus give small results. Let’s see what happens if you simply use the race of the victim instead (the ones in the outlined boxes).

While the right two results have not changed (i.e. white killing white and black killing black), the results in the two left columns are drastically different and show that whites killing blacks is now a larger figure that blacks killing whites, the exact opposite result as in the Facebook posting.

The full article in (*1) gives a more complete argument than I have made here. But it’s pretty obvious that this is yet another example of “Figures don’t lie, but liars figure.”

Notes:

*1 - https://www.reuters.com/article/uk-fact-check-bar-graph-black-white-homi/fact-check-misleading-bar-graph-presents-distorted-interpretation-of-black-and-white-murder-rates-idUSKBN23M2SX