In order to quantify the effect of retailers, we put retailer dummy in the model so that we can estimate the price difference between the OBMCRs and Dotcoms. To see the price movement over time, two time trend variables are included in the model: TOBMCR, the time trend for the average price of OBMCRs, and TDotcom, the time trend for the average price of
Dotcoms. To control for the toy item effects, we use the variable ListPrice.