We propose a method to compare software products developed by the same company in the same domain. Our method, which measures the time series of the number of detected faults, employs software reliability growth models (SRGMs). SRGMs describe the relations between faults and the time necessary to detect them. Herein our method is extended to classify past projects for comparison to current projects to help managers and developers decide when to end the test phases or release a project. Past projects are classified by three parameters: lines of code, number of test cases, and test density. Then SRGM is applied. Our extended method is applied to the datasets for nine projects developed by Sumitomo Electric Industries, Ltd. Classification by test density produces the best results.