Implicit in these and other comments is that there is some minimum number of participants in order to have a successful bazaar. Appropriate units for effective power are participant-hours per week. This could also be defined as the integral of contribution to a specific activity over all participants. Bazaars may have very large effective sizes for some activities and not others. This may be due to lack of motivation or inability to contribute.
Effective power is a function of effective size AND the activity level of the participants.
It is possible to have one participant contribute more or less than another. One highly active participant may contribute as much work per week as 5 or 10 less active ones combined. Bazaars with more highly motivated and active individuals have larger effective powers. An individual person may move between different profiles over time, or even play roles in multiple profiles simultaneously. This participant is using the product solely because it fulfills a need or goal.