A Common Size Income Statement is an extremely useful tool for financial analysis. It allows you to compare the performance of a company over time or against its competitors by expressing each line item as a percentage of revenue or sales. This makes it easy to see how each part of the business is performing and where potential improvements could be made.Vertical analysis can also be used to identify trends in a company's finances, such as increasing costs or declining profits. By comparing common size statements from different periods, you can spot these trends and take corrective action before they cause too much damage.Overall, using a common size income statement is an excellent way to get a clear picture of how well your business is performing financially. It's quick and easy to use, and provides valuable insights that can help you make informed decisions about the future of your company.