It looks like RAND laid a goose egg with this study.  Kudos to Peterson for exposing this.

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The Philadelphia Story

By PAUL E. PETERSON
February 23, 2007; Page A11

http://online.wsj.com/article/SB117220052178416971-search.html

Judging by test-score results, Philadelphia schools have been enjoying a renaissance over the past four years. Thirty-two percent of Philadelphia's fifth-graders achieved proficiency on the Pennsylvania reading test in 2006, as compared to just 21% in 2002; math proficiency rose to 41% from 19%. At the eighth-grade level, there were 20 percentage point uptics in both reading and math.

Nevertheless, the respected RAND Corporation, in a study expected to influence the report of the Accountability Review Council for the Philadelphia schools that will be released later today, claims these positive results -- which came after a series of reforms including the engagement of private firms in the management of 45 schools -- are in fact deceptive and misleading.