Regression examples that we have seen included explanatory variables such as income, price of the good, prices of related goods, and geographic area. Assume that you have been asked to forecast demand for your company's new product, signature t-shirts. What explanatory variables would you initially include (and test) to forecast domestic sales? What impact would you expect each of them to have on demand? Would you include anything different if you were asked to forecast international sales? If so, what would be different? Why?