The quality of an entire process can be measured by its yield, which is calculated as the ratio of good results to the totality of results.
That is, yield = number of good results / total number of results.
The concept and calculation are the same for each individual process step.
For this reason, it is easy to think that the quality of the entire process would be the same as that of the individual steps, but this is wrong.
Instead, the process yield is equal to the multiplication of all individual step yields.
FTY (first-time yield) = step1 yield times step 2 yield times ... the yield of the last step
Because yield figures are always lower than 1.0, the end-to-end process yield will only get lower when there are more steps, due to accumulated quality loses in each step.
To improve end-to-end quality, reduce the numer of steps and increase the yield of each remaining step.
This requires recognizing that the performance of each step impacts that of the next step.