O'Brien, G. E., Biglan, A., & Penna, J. (1972). Measurement of the distribution of potential influence and participation in groups and organizations. Journal of Applied Psychology, 56(1), 11-18.
http://dx.doi.org/10.1037/h0032138
Developed an index from the assumption that the potential influence of persons in a group can be represented by the number of connections that they have to the task system. Using structural role theory, these connections were derived from both the formal and informal structure of the group. A distinction was then made between influence and participation. Application of the index is illustrated in a study dealing with leader influence and group performance. (PsycINFO Database Record (c) 2016 APA, all rights reserved)