摘要：This study provides ex ante estimates of the value to society of the U.S. Department of Agriculture's witch· weed program. Program objectives are to contain and eradicate witchweed, a semiparasitic plant which reduces corn and grain sorghum yields. Critical elements which determine the social value are cost of the program, price elasticities of supply and demand, and shifts in supply occurring in the absence of a program.
关键词：Witchweed;consumers' surplus;program evaluation;social rate of return;benefit-cost ratio
