Edison Scores Up?

From Edison's press release:

Edison Schools (Nasdaq: EDSN), the nation's largest private manager of public schools, announced today that achievement gains at its schools far exceed, by ratios as high as 5 to 1 and by an overall average of more than double, those gains at similar schools in the locales where Edison is working.

Edison compared each one of its schools to every other "similar" public school within the same district. Similar schools were defined as those serving students with similar levels of economic disadvantage (as determined by free- or reduced-price lunch eligibility) and a similar demographic population (Edison's overall national demographic includes 88 percent minority enrollment) within plus or minus 10 percentage points of the Edison school. For example, if 73 percent of students in an Edison school were eligible for free- or reduced-price lunches (Edison's national average eligibility level), then that Edison school was compared with those schools with free- or reduced-price lunch percentages ranging from 63 percent to 83 percent (and serving the same tested grade levels).

Edison's comparably superior performance is true not only for gains made during the last academic year, but also for cumulative gains made since Edison began its management. For the 2001-2002 academic year, Edison schools with comparison schools available gained an average of 4.4 percentage points on criterion referenced tests and 4.3 percentiles on norm referenced tests; the gains at more than 1,000 comparable schools were 0.7 percentage points and -0.4 percentiles, respectively. Essentially, the comparable schools made no academic gains last year, while the Edison schools gained solidly. Viewed over the period of time since Edison began management at each school, the results are similar. Edison schools with comparison schools available have improved by an average of 3.6 percentage points every year on criterion
referenced tests and 5.5 percentiles on norm referenced tests. Comparable schools have gained only 1.4 percentage points and 2.7 percentiles, respectively-approximately one half of Edison's improvement rate.

I'm sure the negative analysis for why Edison has not really raised test scores will begin soon.