1. A computer-implemented method for transforming transactional data into a forecast and confidence interval for controlling a commerce system, the method comprising: moving goods between members of a commerce system; recording transaction data related to movement of goods between the members of the commerce system, the transaction data including price, product, time, and promotion; estimating, by a processor, model parameters based on the transactional data using a demand model to generate a forecast of demand for the goods based on a proposed price or promotion; determining, by the processor, a confidence interval of the certainty associated with the forecast of demand for the goods based on the proposed price or promotion wherein the confidence interval includes an upper and lower boundary defined by U{tilde over (S)} high,d (t)=U{tilde over (S)}(t)+√{square root over (Δ high,d 2 (t)+Δ stat,d 2 (t))}{square root over (Δ high,d 2 (t)+Δ stat,d 2 (t))} and U{tilde over (S)} low,d (t)=U{tilde over (S)}(t)−√{square root over (Δ low,d 2 (t)+Δ stat,d 2 (t))}{square root over (Δ low,d 2 (t)+Δ stat,d 2 (t))}, respectively, where: t is a time index indicating a specific time interval of an arbitrary length; d is a desired confidence interval percentage; U{tilde over (S)}(t) is forecasted unit sales as a function of t; Δ high,d (t) is a difference between U{tilde over (S)}(t) and a upper value of the forecasted unit sales based on the demand model parameters and d; Δ low,d (t) is a difference between U{tilde over (S)}(t) and a lower value of the forecasted unit sales based on the demand model parameters and d; Δ stat,d (t) is an expected statistical uncertainty in the forecast value as a function of d; U{tilde over (S)} high,d (t) is an upper boundary of the forecast confidence interval including the upper model uncertainty and statistical uncertainty as a function of d; and U{tilde over (S)} low,d (t) is the lower boundary of the forecast confidence interval including the upper model uncertainty and statistical uncertainty as a function of d; and providing the forecast of demand for the goods and confidence interval to a member of the commerce system to control the movement of goods in the commerce system based on the forecast of demand for the goods and confidence interval.