1. ACCEPTANCE
SAMPLING
PRESENTED BY
SREEDEVI K.N
M.Sc INDUSTRIAL FISHERIES
III SEMESTER

2. INTRODUCTION
 Quality control is an activity in which measures are
taken to control quality of future output.
 Sampling refers to observation of a population or
lot for the purpose of obtaining some information
about it.
 Acceptance sampling is a quality control technique.

3. DEFINITION
 Acceptance sampling is defined as sampling
inspection in which decisions are made to accept
or reject products or services.
 It is a decision making tool by which a
conclusion is reached regarding the acceptability
of lot.

4. ADVANTAGES
 Acceptance sampling eliminates or rectifies poor lots &
improve overall quality of product.
 Reduces inspection costs & risk.
 In inspection of sample greater care will be taken so
that results may be more accurate.
 A rejected lot is frequently a signal to the manufacturer
that the process should be improved.
 It provides a no of alternative plans in which a single
sample is taken, two or indefinite no of samples may be
taken from a single lot.

5. SAMPLING PLANS
ATTRIBUTES SAMPLING VARIABLE SAMPLING
1. SINGLE SAMPLING
2. DOUBLE SAMPLING
3. MULTIPLE SAMPLING
4. SEQUENTIAL
SAMPLING

6. ATTRIBUTES SAMPLING PLAN
 Attributes sampling is most commonly used,
more than 1 type of quality characteristics can be
considered for each sample.
 Measurements are simpler to make.
 It requires a larger sample size than variables
sampling plan.

7. SINGLE SAMPLING
 A plan in which inspector is forced to make a
decision concerning acceptability of a lot or batch
on the basis of inspection of units in one sample
taken from that lot.
 It can be described in terms of 3 constants.
 N,the lot size
 n,the sample size
 c,the acceptance number
 c is the maximum allowable defects in sample
 If sample contains c or fewer defectives, lot will be
accepted & if it contains more than c lot will be
rejected.

8. DOUBLE SAMPLING
 These are characterized by two sample size along with
two sets of acceptance rejection numbers.
 The two sample sizes may or may not be equal.
 It can be described in terms of c1,c2,n1,n2
MULTIPLE SAMPLING
• In this 3 or more samples might be taken
before a decision is reached regarding the
acceptability of a lot.
• It results in smaller average sample size.

9. SEQUENTIAL SAMPLING
 An extreme case of multiple sampling in which
sampling might continues until the lot is exhausted.
 It calls for inspection on an item by item basis.
 Decision is made after each item is inspected
concerning whether lot should be accepted or rejected
or sampling continued.
 Sampling & decision making continues until a clear cut
decision is obtained either to accept or reject.

10. VARIABLE SAMPLING
 Variables plan need measurement type data &
decision must be based only on one such
measurement characteristics.
 It is efficient because variables carry more
information than attributes.
 Based on mean & standard deviation
characteristics.
 They are difficult to use.

11. OPERATING CHARACTERISTIC
CURVE (oc)
 A curve which serves to describe an acceptance
plan in terms of probability of accepting lots of
various quality levels with the plan.
Pa =probability of accepting a lot
P` =actual proportion of defectives
pa
p`

12. SAMPLING RISKS
 Both producer & consumer will agree on two
proportions to represent the acceptable
proportion of defectives in the lot.
 AQL(accaptable quality level) : it represents the maxi
proportion of defectives acceptable by consumer.
 LTPD(lot tolerance percent defective): it represents
the mini proportion of defectives which consumer
finds unacceptable.

13. AVERAGE OUTGOING QUALITY
 AOQ is the average quality in terms of fraction or %
defectives for inspection operations.
 These are done under 2 conditions such as rejected lots
be screened &all defectives that contain be replaced by
good articles, lot sizes of product be constant.
 The maxi value of AOQ is average outgoing quality
limit(AOQL).
 Each acceptance sampling plan can be described in
terms of AOQL it will generate.

14. ACCEPTANCE SAMPLING SYSTEMS
 American national standard, sampling procedures and
tables for inspection by attributes is a sampling system
indexed by lot size ranges, inspection levels AQLs.
 The use of sampling schemes defined in this system will
constrain the producer to provide product of quality at
or better than selected AQL.
 Dodge Romig system, Dodge Romig sampling
inspection tables are designed to minimize average total
inspection for a given AOQL.

15. CONCLUSION
 Acceptance sampling is a statistical procedure used to
determine whether to accept or reject a production lot of
material.
 A wide variety of sampling plans are available.plans have
an accepted AQL & a rejected LTPD & an AOQL.
 Acceptance sampling tables are there to supply a set of
accepted procedures with known properties &verified
results.
 Sampling provides rational means of verification that a
production lot confirms with requirements of technical
specifications.