Ending deception in school safety reports

Jay Matthews:

There was something strange in The Washington Post a week ago. A chart on page A16, using data provided by the D.C. public school system, showed that in late summer and fall 2009, Spingarn High School had by far the lowest number of assaults, thefts, threats and other crimes. There were just six incidents in four months compared with an average of 31 in the other eight high schools assessed.
At that time, teachers at this allegedly safest of all regular D.C. high schools were reporting a rash of crimes and classroom intrusions. The situation became so intolerable that by January they had persuaded D.C. Schools Chancellor Michelle A. Rhee to replace the Spingarn principal.
How could the incidents being reported by security guards under school district rules be so different from what people at the school were experiencing? Why did Rhee ignore the data in changing the school’s leadership and yet her successor, Kaya Henderson, used data from similar security incident reports last week to replace the principal at Dunbar High?