Not in that business, but normally you expect certain types of shovels to be seasonal. E.g. snow shovels probably sell more in winter, gardening shovels more in

Not in that business, but normally you expect certain types of shovels to be seasonal. E.g. snow shovels probably sell more in winter, gardening shovels more in summer. Add to that you can usually look at weather data and refine the seasonal estimates, since in a warm winter people buy fewer snow shovels, in a cold spring, people buy fewer gardening shovels. Just put all that into some simple regression models and you probably get a fairly good estimate. The trickiest thing is figuring out how out of stock you are. How many shovels would you have sold if you hadn't run out of stock. So usually you have to be more careful with data points when you might have not registered customers that didn't get what they want in your store.