Six Sigma Tools: Rolled Throughput Yield
Rolled Throughput Yield (RTY) is a measurement metric that illustrates the losses due to rework or corrective action. The beauty of this metric is that is shows in statistical fact the relationship between the defects and the cost of poor quality. This is the tool that most management asks for without knowing the name.
What does it look like?
RTY is generally illustrated in the Poisson Model as pictured below
What doesn’t it do?
While the RTY metric provides a great visual presentation for the improvement areas and the cost of not doing those improvements, it requires a lot of data. Most companies unfortunately do not make a habit of recording specific defect data, and if your company does not have access to this data it really isn’t cost effective to put in software to capture it. If you don’t have access to the data, you are going to be operating on a kind of forecast based on what you do have access to. I do have to caution you that if your process has more than 10% defects, RTY should not be you focus. Identifying root cause should be your priority.
Now that we have gone over some metric types, you should have at least a basic understanding of why the metric is done and what it tells you. As always this is just a launch pad, your belt will be able to help you with the specifics and creating a metric that will be useful to your organization.