The conclusions that can accurately be drawn are quite limited; we can only say that active learning (as an umbrella term) was generally more effective than lecture (as an umbrella term). However, we cannot pinpoint why active learning courses were generally more effective nor can we make claims that any specific type of active learning (e.g., group discussions, flipped classes, inquiry-based learning) is effective. We also cannot say that lecture is ineffective. For specific conclusions to be drawn (e.g., those relating to which forms of active learning are most effective), we need a systematic study of this approach by isolating and comparing defined and unambiguous features of active learning implementations.