 He also argues for '"decentralized diffusion"' (a process where diffusion of any product or practice is propagated by multiple actors) as one of the strategies to achieve this end.Singhal's main contribution lies in the adoption of positive deviance (or PD) approach to research.He argues that solutions to complex social problems exist in the communities as some type of tacit knowledge but are hidden from plain view, and PD approach comes in handy in identifying the tacit knowledge and expanding its prevalence within the community.