Secondary Metrics are used to monitor the unintended consequences of the process changes. Secondary Metrics are chosen carefully so as to ensure that improvements in one part of the value chain does not cause negatively impact another part of value chain. More than one Secondary Metric may be required for each Primary Metric e.g a project around improving cycle time may have an adverse impact on error rates ie. Doing work faster may result in more errors (in such a case we will have the error rates as a secondary metric to ensure that while we improve cycle time we are not adversely impacting error rates).
