Ideally, we would be able to evaluate the effectiveness of small
schools by utilizing some sort of random assignment mechanism.
Some recent studies of school reforms – including the Bloom and
Unterman (2014) and Abdulkadiroglu et al. (2013) papers on small
schools in New York – have used variation induced by randomized
lotteries that are often used to allocate school admissions when
there are more students who want to participate in a program than
can be accommodated. In a classic lottery-style setup, students
would be randomly assigned by a lottery to attend the new school
or not from a school’s application pool, and then the students who
were assigned to attend the new school would be compared to
those who lost the lottery. The students who signed up for the lottery
likely share some similar characteristics – they may have
highly motivated parents who are looking for the best available
educational opportunity, or they may be students who feel they
were not served well by the old school, or they may be students
who faced academic or disciplinary problems at their prior school.
The key feature for evaluation is that once the students identified
themselves as being interested in changing schools, no characteristics
predict whether they were selected from the list of applicants
to attend the new school. As a result, the lottery ‘‘winners’’ and
‘‘losers’’ share the same distribution of prior achievement, family
characteristics, etc. Since the groups are on average the same at
the beginning of the year, any average difference at the end of
the year would be due to the impact of the new school.
Unfortunately, in this case there are no such lotteries available to
use to help isolate the treatment effect of attending a small schoo