Washington University
Sever Institute of Technology
Department of Engineering and Policy

Declared-Strategy Voting: An Instrument for Group Decision-Making

by Lorrie Faith Cranor

Prepared under the direction of Ron K. Cytron

A dissertation presented to the Sever Institute of
Washington University in partial fulfillment
of the requirements for the degree of
Doctor of Science
December, 1996
Saint Louis, Missouri

The goal of this research is to determine whether declared-strategy voting (DSV) can be an effective tool for group decision-making. DSV is a novel group decision-making procedure in which preference is specified using voting strategies--first-order mathematical functions that specify a choice in terms of zero or more parameters. Three ideas motivate DSV: the possibility of taking advantage of electronic voting systems to achieve more beneficial methods of vote aggregation than are feasible with traditional voting systems, the desire to find an information-neutral voting system, and the desire to maximize a voting system's expressiveness. We present designs for two types of DSV systems: batch DSV and ballot-by-ballot DSV. We also develop a rational-strategy formulator that can determine optimal strategies for each voter given only the voter's cardinal utilities for each alternative. Our strategy formulator is based on the expected-utility model of voting and employs a novel technique for calculating pivot probabilities. We present the results of a DSV acceptability study as well as DSV simulations of several types of voting situations.

DSV may be applied to group decision-making situations in which a policy-maker must make a decision using a non-binding survey as a guide, as well as to situations in which a large or small group must make a decision through a binding vote. We demonstrate that DSV can help a decision-maker analyze group preferences. DSV is useful for gauging strength of preference and level indifference, identifying sets of alternatives that act as mutual substitutes, and determining which alternatives voters would support if they knew their favorite was not a serious contender. We also show that DSV can be effective as a voting system. DSV allows voters to vote strategically, maximizing the effectiveness of their votes regardless of whether they have obtained information about the preferences of the rest of the voters or whether they know how to formulate optimal strategies. DSV also allows voters to express their sincere preferences, including preference intensities, without sacrificing the effectiveness of their votes.

copyright by
Lorrie Faith Cranor

to my parents, who taught me how to play the game


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