Multiattribute acceptance sampling plans - Library(ISI Kolkata ...
Multiattribute acceptance sampling plans - Library(ISI Kolkata ...
Multiattribute acceptance sampling plans - Library(ISI Kolkata ...
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increasing in each a i . Note that a j = 0 implies a i = 0 for all i ≤ j. It therefore follows from<br />
(1.2.18) and (1.2.19) that<br />
...(1.2.20)<br />
This proves the theorem.<br />
The above property of the plan A therefore allows us to order the attributes in order of<br />
relative discriminating power. If the attributes are ordered in the ascending order of AQL<br />
value, then it is possible to construct a <strong>sampling</strong> scheme ensuring an acceptable producer’s<br />
risk and also satisfy the condition Slope i ≥ Slope i+1 , for all m, i = 1, 2, ..., r − 1. For<br />
comparison m i /m is kept fixed, i = 1, 2, ..., r.<br />
1.2.7 Construction of A kind MASSP’s using the sample size and AQL from<br />
MIL-STD-105D<br />
Using the set of n. AQL values chosen from MIL-STD-105D, we shall illustrate this for r =<br />
3. There are 13 n. AQL values. We get 286 combinations such that n.AQL 1 < n.AQL 2 <<br />
n.AQL 3 . We further order the triplets lexicographically, considering the n.AQL’s in their<br />
natural order.<br />
We start with the first combination of triplet (0.1256, 0.1991, 0.3155) and choose a 1 =<br />
1, a 2 = 1,and a 3 = 2. This gives producer’s risk of around 5.5 %. All other sets of <strong>acceptance</strong><br />
numbers are worked out such that a plan positioned at a higher level will have a lesser<br />
producer’s risk, so that producer’s risk decreases up to a level of 5% and thereafter it is kept<br />
at less than 5%.<br />
The results of this exercise are presented in Table 1.2.4. Using the notation ρ i =<br />
AQL i /(AQL 1 + AQL 2 + AQL 3 ) we have defined p (3) 0.1 as the value of the p such that,<br />
P A(a 1 , a 2 , a 3 ; npρ 1 , npρ 2 , npρ 3 ) = 0.1.<br />
It is heartening to note that the ratio of the p (3) 0.1 to T otalAQL as defined is also decreasing<br />
from 2.3 to 1.4 with increase in n.T otalAQL, so that the OC appears to be quite steep.<br />
1.2.8 The D kind <strong>plans</strong><br />
Consider the MASSP where we take a sample of size n, observe the number of defectives<br />
(defects) for the i th attribute as x i for all i = 1, 2, ..., r and apply the <strong>acceptance</strong> rule:<br />
accept if x 1 + x 2 + ... + x r ≤ k ; reject otherwise<br />
The probability of <strong>acceptance</strong> at p = (p 1 , p 2 , ..., p r ) under Poisson conditions :<br />
P D(k; m 1 , m 2 , .., m r ) =<br />
k∑<br />
x 1 =0<br />
k−x ∑(r−1)<br />
...<br />
x r=0<br />
r∏<br />
g(x i , m i )<br />
i=1<br />
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