6. Financial statements for the past five years. Evaluate these statements, including all books and financial records, and compare them to their tax returns. This is especially important for determining the earning power of the business. The sales and operating ratios should be examined with the help of an accountant familiar with the type of business you are considering. The operating ratios should also be compared against industry ratios which can be found in annual reports produced by Robert Morris& Associates as well as Dun& Bradstreet.