1. A method comprising: accessing, on a computer processor, past prescription drug utilization associated with at least some of a plurality of plan participants, the past prescription drug utilization including identification and quantity of a plurality of prescription drugs used by a particular plan participant of at least some of the plurality of plan participants; accessing, on the computer processor, drug utilization trend information reflecting changes to prescription drug cost; projecting, on the computer processor, for each of the plurality of plan participants a projected prescription drug utilization based on the past prescription drug utilization and the drug utilization trend information; accessing, on the computer processor, a statistical sample taken from the plurality of plan participants of a plan preference of a first proposed design plan or a second proposed design plan; accessing, on the computer processor, historical plan selection decision data associated with at least a portion of the plurality of plan participants; accessing, on the computer processor, selection preference data associated with a population segment having a similar grouping characteristic to the plurality of plan participants, the population segment including a plurality of persons that are not among the plurality of plan participants; determining, on the computer processor, for each of the plurality of plan participants a perceived plan preference of a first proposed design plan or a second proposed design plan based on a presumed participant objective to minimize participant cost, the statistical sample taken of the plan preference, the historical plan selection decision data, and the selection preference data associated with the population segment having the similar grouping characteristic; determining, on the computer processor, an estimated cost for participation of each of the plurality of plan participants in either the first proposed design plan or the second proposed design plan based on a determination of the perceived plan preference; aggregating, on the computer processor, the estimated cost for the plurality of plan participants to calculate a total estimated cost for the participation of each of the plurality of plan participants in either the first proposed design plan or the second proposed design plan; accessing, on the computer processor, a total target cost for the plurality of plan participants to participate in either the first proposed design plan or the second proposed design plan; determining, on the computer processor, a difference between the total estimated cost and the total target cost; automatically adjusting, on the computer processor, the first plurality of plan design options associated with the first prescription drug benefit plan and the second plurality of plan design options associated with the second prescription drug benefit plan based on a determination of the difference; assembling, on the computer processor, the adjusted first plurality of plan design options into a first adjusted proposed design plan; assembling, on the computer processor, the second adjusted plurality of plan design options into a second adjusted proposed design plan, the second adjusted plurality of plan design options being different than the first adjusted plurality of plan design options; determining, on the computer processor, for each of the plurality of plan participants a perceived plan preference of the first adjusted proposed design plan or the second adjusted proposed design plan based on the presumed participant objective to minimize participant cost, the statistical sample taken of the plan preference, the historical plan selection decision data, and the selection preference data associated with the population segment having the similar grouping characteristic; determining, on the computer processor, an adjusted estimated cost for participation of each of the plurality of plan participants in either the first adjusted proposed design plan or the second adjusted proposed design plan based on a determination of the perceived plan preference; and aggregating, on the computer processor, the adjusted estimated cost for the plurality of plan participants to calculate a total adjusted estimated cost for the participation of each of the plurality of plan participants in either the first adjusted proposed design plan or the second adjusted proposed design plan.