30 November 2011

Sometimes You Have to Take a Closer Look

Under the "how to lie with statistics" category, Jerry Pournelle offers a simple puzzler. See if you can solve it:
Some Teachers Unions have pointed out that the average grade and high school performances in Wisconsin, which has teachers unions, are higher than the corresponding averages in Texas, which is a right to work state. This is true. The average student performance in Wisconsin is higher than the average student performance in Texas.

It is also true that the average black student performance in Texas is higher than black student performance in Wisconsin. The average Hispanic student performance in Texas is higher than the average Hispanic student performance in Wisconsin. The average white (non-Latino) student performance in Texas is higher than the average white (non-Latino) student performance in Wisconsin. The three classes are collectively exhaustive.

These facts are true, and they are not contradictory although they may appear to be. We’ll talk more about this next week, but if you are moved to comment I’m listening. _Pournelle
Jerry's simple puzzle is meant as food for thought. While the teacher's unions in Wisconsin claim that the higher average grades and scores in their state reflects upon the "superiority of union teachers," what it actually shows is something quite different -- and extremely politically incorrect.

Similar phenomena which appear to be paradoxical at the surface level, prove to be rather commonplace when one understands the dynamic processes involved at deeper levels. Anyone interested in the IQ debates might want to take a look at this Wall Street Journal article that attempts to deny the importance of IQ test scores. See if you can count all the logical fallacies (non sequiturs etc), and outright falsehoods.

Anyone with similar puzzles or examples of lying with statistics, feel free to share.

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2 Comments:

Blogger James said...

The answer to JErry Pournelle's question seemed so obvious when I read it, that I thought he was kidding.

Obviously, Texas has more black and hispanic students than Wisconsin, which explains everything.

Thursday, 01 December, 2011  
Blogger al fin said...

Sounds reasonable. But by saying that, you are suggesting something about the relative aptitudes of various groups which no self-respecting teachers' union of the US Democratic Party persuasion would ever say out loud.

It is one of those situations where it would have been better for the special interest spokesperson to have kept his mouth shut.

Thursday, 01 December, 2011  

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“During times of universal deceit, telling the truth becomes a revolutionary act” _George Orwell

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