MIL-STD-1916 DOD Preferred Methods for Acceptance of ProductThe purpose of this standard is to encourage defense contractors and other commercial organizations supplying goods and services to the U.S. Government to submit efficient and effective process control prevention procedures in place of prescribed sampling requirements.

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MIL-STD-1916

APPENDIX

with the acceptability criteria is to be determined. Computations are shown in figure 2. The lot is accepted since it meets all applicable acceptability criteria.

30.3 Variables sampling (double-sided specification limit case). The minimum temperature of operation for a certain device is specified as 180 (measured in degrees F). The maximum is 209. Verification level I (VL-I) has been specified. A lot of 40 items is submitted for inspection in accordance with variables sampling. Table III requires a sample of size nv = 4 for code letter A (CL-A). Suppose the measurements obtained are as follows: 197, 188, 184 and 205; and compliance with the acceptability criteria is to be determined. Computations are shown in figure 3. The lot is accepted since it meets all applicable acceptability criteria.

Line	Information Needed	Symbol	Formula	Result	Explanation
1	Sample size	nv		4	See Table III
2	Sum of measurements		x	774
3	Sum of squared measurements		x2	150034
4	Correction factor	CF	2 ( x) I nv	149769	(774)2 I 4
5	Corrected sum of squares	SS	x2 CF	265	150034-149769
6	Sample variance	v	SS I (nv 1)	88.333	265/3
7	Sample standard deviation	s	v	9.399	88.333
8	Sample mean	x	x I nv	193.500	774/4
9	Lower specification limit Upper specification limit	L U		180 209
10	Lower quality index Upper quality index Quality Index	QL QU Q	(x L) I s (U x) I s min(QL,QU)	1.436 1.649 1.436	(193.5-180)/9.399 (209-193.5)/9.399
11	Sample F value	F	s I (U L)	0.324	9.399/(209-180)
12	Number of nonconformances k value F value	C k F		0 1.210 0.370	See Table III See Table III
13	C acceptability criterion k acceptability criterion F acceptability criterion		C = o ? Q k ? F F ?	Yes Yes Yes	1.436 1.210 0.324 0.370
NOTES: The k value is the minimum allowable value for the quality index, Q. The F value is the maximum allowable value for the sample F value, F .

FIGURE 3. Computations for double specification limit case.