Six Sigma Rolled Throughput Yield
- Publication:
- Quality Engineering
- Date:
- December 2001
- Issue:
- Volume 14 Issue 2
- Pages:
- pp. 257-266
- Author(s):
- Graves, Spencer
Abstract
[This abstract is based on the author's abstract.] Rolled throughput yield (RTY) as a measure of overall performance is described and a procedure is provided for computing statistical control limits. Although RTY and total process yield (TPY) are both computed as the product of the yield at each step of a process, Six Sigma proponents define RTY based on Poisson counts of defects, whereas TPY is based on binomial counts of defects. Six Sigma holds that RTY estimates the proportion of units in which no defects are found. For processes with scrap in a parallel step, the number of units may be different in different paths. In such cases neither RTY nor TPY are truly a proportion of units, but they may still provide useful indices of process quality.