Historical analogy method mainly forecasts the demand for a new product, it may be accurate and cheap. It bases on forecasts and past data of any similar or relevant existing products, then according to the product situations to develop a best fit forecast.
For examples, forecasting the demand of iPhone 6 phone cover, can base on the sales of iPhone 6, forecasting the demand of iPhone 6 will base on the sales of iPhone 5; or to forecasting the demand of an new type of camera film can base on the sales of the company’s latest camera. The weakness of this is that it relies on analogy being correct, and there is no guarantee that the new product demand will match.