1. A non-transitory computer-readable medium storing computer-executable instructions that when executed by a computer cause the computer to perform a method, the method comprising: accessing a demand model and retail panel data describing historic demand for a plurality of retail products over time; transforming the retail panel data to cancel effects of base demand and seasonality for a first retail item; solving an elasticity equation using the transformed retail panel data to estimate an elasticity of demand for the first retail item; where the elasticity equation comprises a transformed version of the demand model for the plurality of retail products that has been transformed to cancel effects of base demand and seasonality; estimating base demand and seasonality for the first retail item based, at least in part, on the estimated elasticity of demand for the first retail item and an un-transformed version of the demand model that includes effects of base demand and seasonality; providing the estimated elasticity, base demand, and seasonality for use in determining a sales forecast for the first retail item.