Goyal (2011:71): We need to consider and account for alternative explanations for network effects. For example, if the flow of worker migrants from Country A to Country B correlates to the number of workers from Country A in Country B, it could be that networks are providing information on opportunities or helping adaptation. However, it could just be that people in Country A possess particular skills needed by Country B.
Oliver (2014:3): Notes boundary specification can be problematic in the study of covert networks: kinship ties may be included, even though there is no evidence of these individuals being part of covert network [This is also an ethical issue]
Oliver (2014:3): Argue that tie type and the implications of differences in tie type are not adequately considered.