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Acceptance Sampling: LTPD and AQL (Page 2 of 2)
AQL
- Acceptable Quality Level
The AQL can be determined using the operating
characteristic (OC) curve
by finding that quality level on the bottom axis that corresponds to a
probability of acceptance of 0.95 (95%) on the left axis.
Associated with the AQL is a confidence statement one can make. If the
lot passes the sampling plan, one can state with 95% confidence that the
quality level of the lot is equal to or better than the AQL (i.e., the defective
rate of the lot < AQL).
On the other hand, if the
lot fails the sampling plan, one can state with 95% confidence that the
quality level of the lot is worse than the AQL.
Table 2. AQL Sampling Table based on the Mil-STD-105D
Acceptable Quality Levels for Normal Inspection (% defective)
Lot
Size/
Sample
Size
.01
.015
.025
.04
.065
.10
.15
.25
.40
.65
1.0
1.5
2.5
4.0
Lot
Acceptance (Ac) Number (maximum number of rejects to accept the
lot)
LS=2 to
8
SS=2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
LS=9 to
15
SS=3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
LS=16 to
25
SS=5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
LS=26 to
50
SS=8
0
0
0
0
0
0
0
0
0
0
0
0
1
1
LS=51 to
90
SS=13
0
0
0
0
0
0
0
0
0
0
0
0
1
1
91 to
150
SS=20
0
0
0
0
0
0
0
0
0
0
0
0
1
2
151 to
280
SS=32
0
0
0
0
0
0
0
0
0
0
0
1
2
3
281 to
500
SS=50
0
0
0
0
0
0
0
0
0
0
1
2
3
4
501 to
1200
SS=80
0
0
0
0
0
0
0
0
0
1
2
3
5
7
1201 to
3.2K
SS=125
0
0
0
0
0
0
0
0
1
2
3
5
7
10
3201 to
10K
SS=200
0
0
0
0
0
0
1
1
2
3
5
7
10
14
10001-35K
SS=315
0
0
0
0
0
0
1
2
3
5
7
10
14
21
35001-150K
SS=500
0
0
0
1
1
1
2
3
5
7
10
14
21
-
150001-500K
SS=800
0
0
0
1
1
2
3
5
7
10
14
21
21
-
.01
.015
.025
.04
.065
.10
.15
.25
.40
.65
1.0
1.5
2.5
4.0
See
also:
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www.SiliconFarEast.com.
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