Table 7.

Impact pathway related to the diffusion of innovations

Context	Mechanism	Outcome	Implication for the diarrhoea outcome or its estimation in the study and the Waddington review
Interventions are implemented in communities whose members are linked in social networks; they are also linked, generally less intensively, with people in neighbouring communities.	Information that people gain from interventions and their experience with new practices moves through these networks.	Information from interventions or direct access to infrastructure benefits people in control as well as treatment groups.	Estimates of diarrhoea morbidity reduction based on the difference between treatment and control groups are biased downwards (Torun 1983; Bateman et al. 1995; Shahid et al. 1996; Kremer et al. 2009).