The final component of a quality gate is Evaluation. As with any process that is undertaken an evaluation or review should occur to examine where improvements can be made for future use.
At the end of each statistical process cycle is it recommended that the quality gates should be evaluated to determine what worked well, what didn't and where improvements can be made. It is useful to consider whether the information provided by the quality gates provided enough information to make informed decisions.
Potential improvements for quality gates may include but are not limited to:
- An assessment of the benefit of all the quality measures within each quality gate compared to the cost of having them;
- Adjustments to tolerance levels;
- The addition of quality measures not specified previously;
- The removal of quality measures not considered useful;
- The removal of a quality gate because it does not add value or is not required; and
- An adjustment to all of the components of a particular quality gate based on the experience of the process of using them.
Evaluation of quality gates consolidates the final reporting on the quality of the statistical process cycle. The subsequent documentation and knowledge management that occurs due to this explicit review of the entire statistical process cycle assists with maintaining confidence in the quality of the statistical output produced.