Standard Voting Power Indices Work: An Experimental Investigation of Pure Voting Power

We evaluate the accuracy of power indices by experimentally measuring the political power embodied in blocks of votes per se. The experiment incorporates several subjects interacting in online chat rooms under supervision. Chat rooms and processes for selecting subjects reduce or eliminate extraneous political forces leaving logrolling as the primary political force. Results show that two standard power indices reflect voting power while other power indices and proportionality do not.Voting, Power Index, P Power, Shapley-Shubik, Banzhaf, Johnston, Burgin, Experiment.

Focused Power: Experimental Manifestation of the Shapley-Shubik Power Index

Experiments evaluate the fit of the Shapley-Shubik Power Index to a controlled human environment. Subjects with differing votes divide a fixed purse by majority rule in online chat rooms under supervision. Earnings serve as a measure of power. Chat rooms and processes for selecting subjects reduce or eliminate extraneous political forces, leaving logrolling as the primary political force. Initial proposals by subjects for division of the purse allow measurement of effects from focal points and transaction costs. Net results closely fit the Shapley-Shubik Power Index.Voting, Power Index, Focal Point, Shapley-Shubik, Experiment

Standard voting power indices work : an experimental investigation of pure voting power

We evaluate power indices by experimentally measuring the political power embodied in blocks of votes per se. Subjects with differing votes divide a fixed purse by majority rule in online chat rooms under supermision. Chat rooms and processes for selecting subjects reduce or eliminate extraeous political forces leaving logrolling as the primary political force. Results show that various power indices bracket voting power which is more than proportionally concentrated in large players.<br /

Focused Power: Experiments, the Shapley-Shubik Power Index, and Focal Points [Dataset]

Experiments evaluate the fit of human behaviour to the Shapley-Shubik power index (SSPI), a formula of voter power. Groups of six subjects with differing votes divide a fixed purse by majority rule in online chat rooms. Earnings proxy for measured power. Chat rooms and processes for selecting subjects reduce or eliminate extraneous forces. Logrolling remains as the primary political force. Subjects’ initial proposals for division of the purse allow measurement of effects from focal points and transaction costs. Divisions of purses, net of those effects, closely fit the SSPI, averaging 1.033 of their SSPI values. The SSPI can serve as a control for power imbedded in voting blocs, permitting fuller analysis of other factors that affect political outcomes