I’m driving home from work yesterday and I noticed something different at the intersection by my house. A traffic camera has been installed just in time to give some people a not so merry Christmas present.

Traffic cameras, such as the one I saw, have been introduced as a visual control with the intent to improve safety. Reducing the amount of defects (in this case, an accident) sounds like a worthy Six Sigma project. In fact, studies have shown when placed at intersections, cameras can reduce the chance of drivers’ running a red light. Unfortunately, those same studies also concluded cameras contribute to a higher number of rear ending accidents.

Good intentions are not enough when defining a Six Sigma project. A key question when scoping a project should be “What are the primary and secondary metrics?” Most of us are familiar with a primary metric, a general measurement of how we will deem the project successful.This could be cycle time, throughput rate, added revenue, etc. However, for most projects, secondary metrics are just as important. The secondary metric serves as a “check and balance” to ensure your project has not created problems somewhere else in the process. For example, a project may reduce claim processing time in a certain department but creates additional work in the preceding department, resulting in an increase in the overall processing time (and thus defeating the point of the project). A key manufacturing example is ensuring production throughput increases (primary metric) without increasing the overall scrap rate (secondary metric).

The next time you are defining a Six Sigma project, remember traffic cameras. After all, you don’t want to complete a project to have a zero sum gain in the end.