Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001
· Used to estimate the probability of lot rejection, and design sampling plans.
· Drawing the single sampling curve (assuming Poisson distribution)
· The basic trade-off to be considered when designing sampling plans.
- The producer does not want to have lots with higher rejects than the AQL to be rejected. Typically lots have acceptance levels at 95% when at AQL. This gives a producers risk of α = 100% - 95% = 5%. In real terms this means if products are near the AQL, they have a 5% chance of being rejected even though they are acceptable.
- The consumer/customer does not want to accept clearly unacceptable parts. If the quality is beyond a second unacceptable limit, the LQL (Lower Quality Level) they will typically be accepted 10% of the time, giving a consumers risk of β = 10%. This limit is also known as the LTPD (Lot Tolerance Percent Defective) or RQL (Rejectable Quality Level).
· AOQ (Average Outgoing Quality)
· AOQ (Average Outgoing Quality) - a simple relationship between quality shipped and quality accepted.
· ASN (Average Sample Number) - the number of samples the receiver has to do
· On the other hand, given consumers risk (β) and Lower Quality Level (LQL), we can follow a similar approach, still using the table on pg. 314
· Given α and AQL, and β and LQL we can also find a best fit plan through trial and error.
READING: chapter 8, pg. 283-320
PROBLEMS: pg. 321- #1, 4, 7, 14, 17, 22