A metric trend that jumps in an undesirable direction can stimulate a knee-jerk response to take some action to get the metric back on track. Conversely, metrics trends can reveal warning signs of serious problems that might be ignored by those who don’t want to hear bad news. For example, suppose your product defect densities increase despite the team’s quality improvement efforts. You might conclude the "improvements" are doing more harm than good and be tempted to revert to old ways of working. In reality, better testing and review methods might well find a larger fraction of the defects that are present—this is good!

Monitor the trends that key metrics exhibit over time and don’t overreact to single data points. Make sure you understand the error bars around each of your measures so you can tell whether a trend reversal is significant. For instance, if you can determine why your postrelease defect correction effort has increased in two successive calendar quarters, you can decide if corrective action is required. Allow time for the data you’re collecting to settle into trends. Make sure you understand what the data is saying before you change your course of action.

Many teams struggle with how to implement a sensible metrics program that provides the information needed to manage their projects and organizations more effectively. By staying alert to the 10 risks described here, you can increase the chance of implementing and sustaining a software metrics initiative in your organization.