Almost any study of charter schools or something like the Kipp program have an inherent problem in attempting to track them. Because it takes an effort to get into them, it can be assumed that there is a parent in the background who cares. An educator from tacoma changed my mind on this years ago. Someone challenged him on why private schools performed so much higher on less money. He pointed out that there weren't a lot of crackheads paying for and driving their kids to these schools each day. Then he pointed out that at that time, one out of three kids in the Tacoma School district was involved in some sort of special program. Downs syndrom, autism, blind, wheelchairs, deaf, violent behavior, etc... they all have a right to education and most of this will be done by the public school system. The cost of this puts public schools at a great disadvantage.