Virtual charter schools provide full-time, tuition-free K-12 education through internet-based instruction. Although virtual schools offer a personalized, content-appropriate experience, most research suggests these schools are negatively associated with achievement. Few studies account for differential rates of student mobility, which may produce biased estimates if mobility is jointly associated with virtual school enrollment and subsequent test scores. We account for student mobility in an evaluation of a single, large, anonymous virtual charter school. We estimate treatment effects of the virtual school on student achievement using a hybrid of exact and nearest-neighbor propensity score matching. Relative to their matched peers, we estimate that virtual students produce similar ELA scores and significantly worse math scores after one year. Among a limited sample of students observed for four years, we estimate that virtual students ultimately produce higher ELA scores and similar math scores relative to matched peers. We argue these findings are more reliable indicators of the independent effect of virtual schooling on student achievement because the match on student mobility is a proxy for otherwise unobservable negative selection factors.
virtual schools, charter schools, student mobility, matching, quasi-experimental design, on-line learning
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