
Laws of probability must be considered

Producer’s risk


rejecting a good batch
Consumer’s risk

accepting a bad batch

determines the size and frequency of
sample

basis for accepting or rejecting a product

requires 3 numbers
 N - number of items from where the
sample is drawn
 n - a random sample drawn from a
lot or batch

C – acceptance number ; specified
by AQL (acceptable quality level)

determines the size and frequency of
sample

basis for accepting or rejecting a product

requires 3 numbers
 N - number of items from where the
sample is drawn
 n - a random sample drawn from a
Example
Lot
or Batch
sample
defects
N-50
lot
or batch random

C – acceptance
Reject ornumber
Accept

Square root system
formula:
𝑛=
𝑥=
Example
𝑁+1
2𝑎
N-50
𝑛 = 50 + 1
𝑥=
2𝑎
=

Military
Government
Standards
Sampling
(MILSTD-D
Plan 105D)
Adopted by the US Department
of Defense
Bell Telephone
Engineers
Laboratories - 1942

MASTER TABLE
- Sample size, acceptance and
rejection numbers
NEED TO KNOW
1. AQL
2. SAMPLE
CODE
LETTER
3. TYPES OF
SAMPLING
Simple
Double
Multiple
4. INSPECTION
SCHEMES
Normal
Tightened
Reduced