Sunday, December 10, 2006

Painting an average statistical picture

There are always a number of ways to slice data in order to obtain the statistics that paint the picture you want to sell. The Olentangy District announced with pride that its latest Third Grade Reading Achievement Test scores indicate growth. Based on what? Based on the district beating the average score of its state-selected group of similar districts. Thanks goodness for the few very poor performing districts in that group - it kept the average down for once.

Instead of picking the average of some arbitrary grouping of schools, look at absolute rank across the state based on the Performance Index(PI). The PI is a state statistic that gives a district credit for advanced and accelerated proficiency test scores, and dings a district for scores less than proficient. The PI is the best way to compare districts, that's why it's printed on the annual state report card of district achievement.

So, what does the PI show? Olentangy is ranked 100th out of the state on this indicator of student outcome. Olentangy is also ranked 15th in its group of 21 similar schools (20 schools plus Olentangy). I have always asked: How do you take a district with top demographics, achieve mediocre results, and still find means to celebrate?

For Olentangy, it's certainly a good thing that there are some really poor performing districts. But how do comparisons against the average maximize learning and prepare students for competitive admissions to colleges and universities? Well, they don't.

Go ahead and celebrate mediocrity, it's all we seem to get from the local school system.

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