The MIL-STD-414 mentions five inspection levels to determine the sample size code letter but does not mentions how to select the inspection level, any help is appreciated.
Hi Mohd: As you mentioned there are five levels of inspection (from I to V).
- IV is for normal inspection. This is the level you commonly start with.
- V is for more stringent inspection
- I, II, III is when lower inspection level is required
In some cases, the level of inspection is switched when the conditions change, say from normal to reduced inspection. In the Schilling's book "Acceptance Sampling in Quality Control" (2nd Ed.) you will find more details. Have a look in Chapter 12. They show a switching procedure normal-tightened-reduced.