Since 2012, Ithaka S+R has periodically reviewed the empirical literature on the impact of online and hybrid instruction on student outcomes. As reported in the 2013 review, very few studies employ rigorous methodologies; of those that do, the findings indicate that students do about as well in online or hybrid courses as they do in face-to-face versions of the same course.

For the latest update in this series, “Online Learning in Postsecondary Education: A Review of the Empirical Literature (2013-2014),” Derek Wu reviewed twelve studies published in 2013 and 2014, and reports consistent results.

The most methodologically robust studies find no significant differences in performance between students who took an online or hybrid course and those who took a face-to-face version of the same course. However, only three of the twelve studies used experimental or quasi-experimental research designs that yield a causal inference. The vast majority of studies are vulnerable to various threats to validity, ranging from sample selection and omitted variable bias to inconsistencies in how delivery formats are defined.

The report also identifies several avenues of research that deserve more attention than they have received. Practical subjects such as the cost implications and scalability of online and hybrid instruction, and the impact of particular features of those delivery formats, are rarely studied. Researchers should also focus more attention on differentiating outcomes by course subject and level and by student demographics.

As the number of postsecondary students taking online and hybrid courses increases yearly, there will be both more opportunities and greater need for rigorous research on their effects.