Ego network analysis is extremely convenient because it can be used in conjunction with random sampling, which enables classical statistical techniques to be used to test hypotheses. Complete network analysis is where you try to obtain all the relationships among a set of respondents, such as all the friendships among employees of a given company. Most of the rhetoric surrounding network analysis is based on complete networks. Techniques such as subgroup analysis, equivalence analysis and measures like centrality all require complete networks. The field of network analysis is conventionally criticized for being too much methodological and too little theoretical.
Critics say that there are few truly network theories of substantive phenomena.
This is not a well-considered argument, however, because when examples of network theories are presented, critics say 'that's not really a network theory'. This is natural because theories that account for, say, psychological phenomena, tend to have a lot of psychological content. Theories that account for sociological phenomena have sociological independent variables. Only theories that explain network phenomena tend to have a lot of network content. With the advent of permutation tests, however, this is much less of problem now.