Henry Schaffer: Misleading statistics

August 22, 2013 

Misleading statistics

There is a wonderful book, “How to Lie with Statistics,” which came to mind reading about graduation rates in the Aug. 15 news article “School leaders want better.”

Apparently we in Wake County have been very pleased for years to have a higher high school graduation rate than the Charlotte-Mecklenburg system. Whoops, this past year Charlotte-Mecklenburg did better and surged past Wake! That makes headlines and is used to bash Wake schools.

But last year, Charlotte-Mecklenburg dropped the credits required to graduate by 14 percent and now requires fewer than Wake does. Hmm ... might that be the reason?

Digging deeper, Charlotte-Mecklenburg used to require more credits than Wake. Might that be the reason for the past difference?

Don’t worry about comparing apples and oranges when you can compare apples and pineapples! (Oops, I’m assuming that a Wake credit equals a Charlotte-Mecklenburg credit – is that a safe assumption?)

Henry Schaffer

Professor emeritus, N.C. State University

Raleigh

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