Design of an impact evaluation using a mixed methods model - an explanatory assessment of the effects of results-based financing mechanisms on maternal healthcare services in Malawi. - Brenner, Stephan; Muula, Adamson S.; Robyn, Paul Jacob; Bärnighausen, Till; Sarker, Malabika; Mathanga, Don P.; Bossert, Thomas; De Allegri, Manuela (BMC Health Services Research, 2014)