Analytical Gap


Earlier today I posted a press release on the Education Equality Index and its claims about schools in Memphis.

I posted the release without comment or analysis.

Fortunately, Bruce Baker provided some analysis regarding this index and other attempts to compare achievement gaps among schools from different states.

Here’s the bottom line: Income gaps explain achievement gaps. That is, states with relatively large income gaps tend to have relatively large achievement gaps. Likewise, states with more income homogeneity tend to have smaller achievement gaps.

I wrote about this on a Tennessee-specific level when talking about the achievement gap and BEP funding increases:

Additionally, during this same ten year time period, the gap between the highest and lowest scores among districts is clearly explained by the gap in per pupil expenditures among those districts. You spend more, you get better results. The impetus for all this spending was the new BEP formula that sent more money to all school systems. Those districts already at the top were most able to take advantage and boost ACT scores while those at the bottom saw an increase in the number of students taking the ACT, resulting in the statewide slight ACT decline Dunn references.

The districts at the top in spending tend to also be the districts with the highest incomes. Thus, TCAP results often serve as good indicators of the relative income level of Tennessee school districts.

Here’s what Baker has to say:

But these assertions – both the old and the new – presume that comparisons of achievement gaps, either by race or income, between states are valid. That is, they validly reflect policy/practice differences across states and not some other factor.

Quite simply, as most commonly measured, they do not. They largely reflect differences in income distributions across states, a nuance I suspect will continue to be overlooked in public discourse and the media. But one can hope.

Achievement gap analysis is interesting and it tells us something. But, as Baker points out, it is important to be clear about what such gaps reveal.

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