We survey the literature on social networks by putting together the economics, sociological and physics … network formation. While the physics/applied mathematics approach is capable of reproducing most observed networks, it does … not explain why they emerge. On the contrary, the economics approach is very precise in explaining why networks emerge but …

groups ; free-rider incentives ; determinants of international environmental cooperation ; public goods experiments …

Field experiments occupy a middle ground between laboratory experiments and naturally occurring field data. The idea is … empirical economics, field experiments provide an advantage by creating exogenous variation in the variables of interest …. -- Field experiments …

Networks contain complex patterns of dependency and require multiple levels of analysis to explain their formation … appropriate theoretical frameworks to examine network-related problems, (iii) understand how networks emerge and produce effects …