A tool with one or more chambers in a manufacturing system is identified as performing at or below an acceptable level by the following steps. Store process data from tools for each one of a plurality of individual processes for a processed object in a process database. Store tool performance data for each individual process for a processed object in a yield database. Develop statistics for similar tool sets associating data with each of the similar tool units. Generate yield numbers for each group of the similar tool units based upon the statistics. Identify poorly/well performing tool units by using the yield numbers.