Abdulkadiroglu et al. (2011) studied the effectiveness of charter schools in the Boston area using a clever research strategy. They utilized the fact that many charter schools in the area are oversubscribed, and thus must assign enrollment slots to students using a randomized lottery. The researchers compared winners and losers of the lottery to estimate the effect of charter school attendance on student achievement, finding large and significant score gains for charter students compared to their peers who lost the lottery.

Based on the results of this experiment, one policy maker has argued that all schools in the state of Massachusetts should be replaced by charter schools. In what ways does the experiment support this policy maker's proposal? Now, considering the other side of the debate, what are some specific reasons for proceeding with caution when applying the results of the experiment to this proposal?