The following is an excerpt from
http://www.trelease-on-reading.com/whatsnu_miracles.html#zerodropoutThat site includes more links on the falsified measures of success of the Houston school system under Superintendent (now Secretary of Education) Rod Paige:
The Texas Education Miracle "went unchallenged until February of 2003 when an assistant principal at Houston's Sharpstown High School couldn't believe his eyes: a "zero" dropout rate for his school. Even though 1000 students had started as freshman and by senior year only 300 were still there, no dropouts. (Left unsaid is that many of the missing 700 were at-risk students who might have brought down the school's scores, a fact uncovered in a similar scandal in New York). When the Houston assistant principal, Robert Kimball, a retired Army lieutenant colonel and Vietnam veteran, looked into the matter, he found a can of worms that resulted in a state audit reducing the academic rating on 15 of the district's 16 middle and high schools that had been rated "outstanding."
In addition to Sharpstown's missing 700, there were an additional 2,300 missing students who should have been labeled "dropout." While many may drop-out, in such instances many also are pushed-out, encouraged to leave by frustrated administrators bent on raising the scores."
"In Houston's case, the incentive to change the academic records was "education mandates" — the ones handed down by the superintendent to principals."