It is only order quantity that to decide for a spot selling time in the classical newsboy problem. It follows that the purchase timing and the time-variant variance of forecasted demand are neglected. When the vendor gives a price discount for early purchase, the buyer purchases the quantities of price discount at the cost of forecast bias. When the buyer forecasts the demand for advancing purchase, it may increase the variance of the forecasted demand, which is forecast bias. We try to embed this forecast bias into the model in this paper. A mathematical inventory model in a distribution free newsboy problem was proposed, which the purchase timing and order quantity were considered as decision variables in this paper. The resultant outcomes could apply to some cases in futures commodity contracts.
Tamsui Oxford Journal of Management Sciences 13-14, pp.1-13