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Rolled Throughput Yield (RTY) is a term used in Six Sigma. It is the probability that a unit can pass through a process without defects. It is the product of the first pass yields at each step:
RTY = y1 x y2 x y3 x
..yn
where the yi values are the yields at each step before rework.
The argument is that the perceived yield is misleading because it ignores the rework. Management often do not realize, or measure. the amount of rework that occurs within a process and it can be extremely large. Because of this it is sometimes known as the 'hidden factory'. Consider an example:
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Defects
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Scrap
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Rework
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Units
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DPU
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FPY
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RTY
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|
1
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10
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5
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5
|
100
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0.100
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0.905
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0.905
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|
2
|
12
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5
|
7
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95
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0.126
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0.881
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0.797
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|
3
|
8
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0
|
8
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90
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0.089
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0.915
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0.730
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|
4
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10
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5
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5
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90
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0.111
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0.895
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0.653
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5
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5
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1
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4
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85
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0.059
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0.943
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0.616
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| Totals |
45
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|
|
460
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0.485
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0.616
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Follow the link for other Six Sigma Metrics.
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