Acceptance Sampling
By: Cori Rosoff
Penn State University
OISM 470W
Short Synopsis
• Acceptance sampling Defined
• When is acceptance sampling
useful?
• The risks associated with
acceptance sampling
Short Synopsis
• Disadvantages of acceptance
sampling
• Application of acceptance
sampling
• MoonLight Jeans example
Acceptance Sampling
Defined
• Acceptance Sampling is a form
of inspection that is used to
determine whether or not goods
are coherent with a set
standard of quality
Acceptance Sampling
• How can this tool be used in
your organization?
When is Acceptance
Sampling useful?
• When product testing is
– destructive
– expensive
– time consuming
• When developing new products
When is Acceptance
Sampling useful?
• When dealing with new
suppliers
• When a supplier’s product has
had excellent quality in the past
Risks of Acceptance
Sampling
• Producers Risk
– The risk associated with a
producer rejecting a lot of
materials that actually have good
quality
• Also referred to
as a Type I Error
Risks of Acceptance
Sampling
• Consumers Risk
– The risk associated with a
consumer accepting a lot of
materials that actually have poor
quality
• Also referred to
as a Type II Error
Acceptance Sampling
• Acceptance sampling is a
process that helps to determine
whether to accept or reject the
sample being observed
Disadvantages of
acceptance sampling
• The process of the goods being
inspected is not improved
When can acceptance
sampling be applied?
• At any point in production
• The output of one stage is the
input of the next
When can acceptance
sampling be applied?
• Sampling at the Input stage
– Prevents goods that don’t meet
standards from entering into the
process
– This saves rework time and money
When can acceptance
sampling be applied?
• Sampling at the Output stage
– Can reduce the risk of bad quality
being passed on from the process
to a consumer
– This can prevent the loss of
prestige, customers, and money
When can acceptance
sampling be applied?
• Sampling at the Process stage
– Can help adjust the process and
reduce the amount of poor quality
in production
– Helps to determine the source of
bad production and enables return
for reprocessing before any further
costs may be incurred
Typical Application of
Acceptance Sampling
• A vendor delivers a product to a
manufacturing company
– The product is a raw
material used by the
company
Typical Application of
Acceptance Sampling
• A sample of the shipment is
taken
– Quality characteristics of the units
in the sample are inspected.
Typical Application of
Acceptance Sampling
• Based on the observations
made, the decision is made to
either accept or reject the
entire shipment
Typical Application of
Acceptance Sampling
• The decision to accept or reject
the shipment is based on the
following set standards:
–
–
–
–
Lot size = N
Sample size = n
Acceptance number = c
Defective items = d
• If d <= c, accept lot
• If d > c, reject lot
Acceptance Sampling
Plan
• Mr. Smith owns and operates a
manufacturing plant.
– He receives a shipment of 1,000
sheets of glass.
– Of the shipment, Mr. Smith chooses
to sample 50 sheets.
Acceptance Sampling
Plan
• If more than 2 are defective, he
is sending back the entire
shipment to the supplier.
• Mr. Smith observes 5 defective
sheets of glass.
Acceptance Sampling
Plan
• Therefore, according to the set
standards mentioned above:
–
–
–
–
N = 1,000
n = 50
c=2
d=5
Acceptance Sampling
Plan
• What should Mr. Smith do in
reference to the number of
defective items observed????
Acceptance Sampling
Plan
• Remember, if d > c, reject lot
• Since c = 2, and d = 5…
– Mr. Smith should
reject the lot of
1,000 sheets of glass
MoonLight Jeans
• MoonLight Jeans store receives a
shipment of 300 pairs of jeans from
its warehouse.
• It is common practice for the store to
sample 5% of the total received.
• The acceptance number under any
and all circumstances for MoonLight
Jeans is 10.
MoonLight Jeans
• Of the 15 pairs of jeans
observed, 2 were defective.
• What conclusion should the
store manager come to based
on this information?
MoonLight Jeans
• The store manager has just
found out that the clerk who
inspected the samples made a
huge mistake…
• The actual number of defective
pairs of jeans sampled was 12.
MoonLight Jeans
• What type of risk is involved
with the error made at
MoonLight Jeans?
• How might this error affect the
store and their customers?
Summary
• Acceptance Sampling
– a form of inspection that is used to
determine whether or not goods
are coherent with a set standard of
quality
– It does not improve the process
that the products are derived from
Summary, cont…
• Uses of Acceptance Sampling
• Risks
– Producers Risk
– Consumers Risk
Summary, cont…
• Stages of Inspection
– Input Stage
– Process Stage
– Output Stage
• Example Sampling Plan
• MoonLight Jeans Example
Works Cited
• Canavos, George C. and Don M. Miller.
Custom Edition of Introduction to
Business Statistics 2e. USA:
Brooks/Cole Publishing Company,
2001.
• Foster, S. Thomas. Managing Quality: An
Integrative Approach. New Jersey:
Prentice-Hall Inc., 2001.
• Montgomery, Douglas C. Introduction to
Statistical Quality Control. USA: John
Wiley & Sons, Inc., 1996.
Works Cited, cont…
• Starbird, S. Andrew. “The Effect of
Acceptance Sampling and Risk
Aversion on the Quality Delivered by
Suppliers.” Journal of the Operational
Research Society v45 (1994): 309-320.
• Wetherill, Barrie G. Sampling Inspection
and Quality Control. Great Britain:
Butler & Tanner Ltd, 1969.