The community power studies generally assume that the decisions made by the community are a function of the power exerted on the community by various power holders. They assume some kind of "power field" in which individual powers are summed to produce the final outcome.
The community studies are analytic in the sense that they attempt to infer the power of individuals within the community by observing (either directly or indirectly) their net effects on community choice. That is, the assume that a decision is some function of individual power and the individual preferences. Hence, they observe the decision outcome and the preferences, and estimate the powers.