The common size statements are useful, both, in intra-firm comparisons over different years and also in making inter-firm comparisons for several years. This analysis is also known as

Common-size statement analysis scales individual statement items against a common base within a single reporting window (such as setting Total Assets to $100\%$ on a Balance Sheet or Revenue to $100\%$ on an Income Statement). Because it analyzes items down a single column for a specific point in time, it is called Vertical analysis.