In this paper, a comparison of two purchase policies, i.e., BP (Blind Purchase) policy and SP (Selective Purchase) policy, are tried from an economic viewpoint, considering the following cases : 1) Under the BP policy, the fraction defective of the purchased lot is a random variable.2) Under the SP policy, the lead time is a random variable.Furthemore, the case where the demand rate is a random variable is also discussed.