“…Three (5.4%) [25,55,57] of the nine studies that reviewed blended learning methods, failed to assess the effectiveness of the e-learning intervention independently of the face-to-face teaching. Twenty-six (46.4%) studies [11,12,[14][15][16][17][18][19]23,25,29,30,35,37,[41][42][43]45,46,50,52,56,57,59,62,64] measured the effectiveness of e-learning intervention on the basis of self-reported data. These findings are therefore vulnerable to response bias as well as recall bias, when participants were required to make a post-intervention assessment of their pre-intervention skills, knowledge or confidence [65,66].…”