Study design . Qualitative , quantitative , and mixed - methods studies with a longitudinal element were included ( randomized control trial , non - equivalent control group design , and pre - test / post - test only ) . Other . We only included empirical studies published in peerreviewed journals . We focused on peer - reviewed research because there is a sufficient data within the peer - reviewed literature to answer the research questions and peer - review provides assurance of quality and rigor . We searched English language databases only , but did include articles published in other languages . We included studies from 2009 onwards , because such studies tend to use more rigorous methodologies and incorporate findings from previous research .