The power of a cohesive subgroup within a voting body (Q1063513)

The authors consider the power of a cohesive subgroup as the probability the outcome of majority vote of the whole group would change if all members of the subgroup reverse their votes, given that members outside the group independently vote with probability 1/2 of either choice. They study this as a function of the probability members of the subgroup follow the leader, giving explicit formulas.