August 29, 2005

Dropout statistics in political use

Diane Cardwell's story this morning in the New York Times discusses the political uses of graduation and dropout statistics in the New York City mayoral race. As is common, the use of educational statistics here implies normative judgment: a 44-percent graduation rate must be awful, according to Fernando Ferrer (one of the challengers of Bloomberg), in comparison to the 54-percent rate Bloomberg's campaign cites as evidence of improvement. Assuming accuracy, context is everything: Both are much better than 100 years ago and still absolutely unacceptable in comparison to the country as a whole.

Keep the limits of dropout and graduation statistics in mind, though: There is no universally agreed-upon method of measuring graduation and dropping out. Even skipping the old method of measuring dropping out (divide counted dropouts by total 9th-12th enrollment), you'll find many problems with what I call quasi-longitudinal methods of looking at enrollment in 9th grade one year and graduation numbers three years and nine months later. Such quasi-longitudinal methods need to adjust for migration paths to have any chance of accuracy. Of the three ways I've seen in the last few years—Jay Greene's, John Robert Warren's, and Haney et al.'s—Warren's is the soundest methodologically. Miao and Haney argue that the Greene stats and theirs show similar results in terms of trends, and that may well be true for recent years at large scales (i.e., states).

However, I am reluctant to trust correlation statistics to judge the soundness of measures that are amenable to demographic analysis. Those correlations will likely not hold for extremely low levels of graduation and for small scales, such as individual districts and schools. Unfortunately, Warren's approach which adjusts for migration is only usable at large scales.

Some aspects of the technical debate are political and accessible to anyone, though: Should graduation rates include GEDs (which leads to higher graduation rates)? Should we exclude expelled students and students with disabilities from the calculation (which would lead to lower graduation rates)? These questions are not technical at all and go to the heart of what we expect from schools.

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Posted in Education policy on August 29, 2005 8:01 AM |