Rolled Throughput Yield (RTY)
This is one of the most important metrics in Business.
Rolled Throughput Yield is the percentage of a product or service delivered through a system or manufacturing line from start to finish without error or defect. This contrasts with First Time Yield (FTY), which is a measure of the ability of a process to transform a product or service without error or defect and deliver it to the next process or customer. RTY is the aggregate product of all the FTYs and has a solution focus as opposed to a single process focus.
The manufacturing industry usually has a very good feel for RTY because in that industry it is easier to quantify a RTY. The challenge for the manufacturing industry is that the RTY changes over time due to inevitable process degradation. RTY is certainly quantifiable in the service and medical industries but individuals in those industries are less familiar with the advantages of knowing the RTY for business or medical systems.
Figure: Two example calculations for RTY showing the impact of FTYs on RTY.
If you know the RTYs for your business systems, are you happy with the results?
Though the manufacturing industry is familiar with the RTY tool, individuals in other industries are not. You can’t use a tool if you don’t know it exists. Since one of Lean Six Sigma’s mantras is “don’t act without data”, if you don’t know the RTY for your systems how would you know where to focus your improvement efforts?
Without RTY computed for your manufacturing line or business system your quality feedback comes from your employees discovering poor quality or your customers discovering the same thing. Either way, it’s an expensive experience.
Lean Business recommends use of RTY as a benchmark against current and future progress. Lean Business recommends starting with your most precious processes. Do some quick analysis to measure whether or not you have some startling quality deficient processes with a poor FTY. You probably already have a feel for your problem areas. You may also have a good feel for how those problem areas negatively impact other areas. If you don’t, now is a good time to start using this tool.
When you have finished this effort you will better understand your ability to deliver quality products or services and know where to direct your improvement efforts. With increased ability to deliver quality, you will inherently decrease cost.