KTMS Radio Commentary
There is a tendency to overuse the word “average” and
misunderstand what it actually means.
Take, for example, “average” test
scores. As we all know, to get an average, you add up all the scores and then
divide by the total number of scores. It is often the case that no individual
score actually falls at the average.
An average isn’t a median or
midpoint. It doesn’t mean that half the scores fall above and below that point.
In fact, you could conceivably have a situation where ALL scores fall ABOVE the
average, except for one score that is so very low, it pulls down the average.
This helps explain the seeming
paradox with SAT scores. For many years the AVERAGE SAT scores were down. But
scores were up for every subgroup that took the test.
That included Blacks, Hispanics,
Asians, Whites, etc. — and scores were up for every academic level represented
— A students, B students, C students.
How, then, could the overall
average be down?
Because although test scores rose
for every academic level, far more C students are now taking part. And even
though scores rose for students learning English, far more of those students
have been taking the test.
So when you dis-ag-gre-gate the
tests and look at every group that took them, you see a success story. But when
you aggregate the tests and look only at the overall average, the picture is
very different.
This is a critical concept in
assessing what needs to be “fixed” in our schools. Sadly, it is far easier to
deal with simple rhetoric than with complicated facts.
