The bulk of research suggests that not only do students who choose to attend charter schools benefit academically but students who remain in traditional public schools also benefit when those schools have to compete with charters. Education is no exception to the general pattern that choice and competition improve outcomes.
The best way to determine how students fare in charter schools is to compare them to students who applied but were not admitted by lottery (which many charter schools are required to hold when oversubscribed). Studies based on lotteries allow the comparison of apples to apples, while other studies, unable to control fully for preexisting differences between the students who attend charters and traditional public schools, end up comparing apples to zebras.
The only lottery-based analyses released so far were conducted by Stanford University economist Caroline Hoxby. Examining New York Citys charter schools, she found that students admitted by lottery experienced significantly greater achievement than those who lost the lottery and were unable to attend charter schools. With Columbia University economist Jonah Rockoff, Hoxby conducted a lottery-based analysis of charter schools in Chicago and found the same thing. Students learn more when they can choose a charter school.
Competition from charter schools also spurs improvement in traditional public schools. Studies conducted in Arizona, Michigan, North Carolina, and Texas—states where charters are numerous enough to challenge traditional public schools—found student achievement increases when traditional public schools are surrounded by more charter schools. When students have alternatives, schools cant take them for granted.
Of course, there are good and bad charter schools, just as there is a mix of traditional public schools. The point is, charters give students more options to find schools that work effectively for them. And giving students those options motivates traditional public schools to be more effective for the students who remain.
Original Source: http://www.businessweek.com/debateroom/archives/2008/03/charter_schools.html