Acceptance Sampling

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Acceptance Sampling

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  • Acceptance Sampling

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

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