Enter your data for Variables Acceptance Sampling (Create/Compare)

Stat > Quality Tools > Acceptance Sampling by Variables > Create/Compare

Create a Sampling Plan

Complete the following steps to determine the sample size and the criteria for accepting or rejecting an entire lot.
  1. From the drop-down, select Create a Sampling Plan.
  2. In Units for quality levels, select Percent defective, Proportion defective, or Defectives per million to represent the level of defectives in the process.
  3. In Acceptable quality level (AQL), enter a number to represent the highest defective rate from a supplier's process that is considered acceptable. You want to design a sampling plan that accepts a particular lot of product at the AQL most of the time.
    Note

    The AQL must be less than the RQL.

  4. In Rejectable quality level (RQL or LTPD), enter a number to represent the highest defective rate that the consumer is willing to tolerate in an individual lot. You want to design a sampling plan that rejects a particular lot of product at the RQL most of the time.
    Note

    The RQL must be greater than the AQL.

  5. In Producer’s risk (Alpha), enter a value between 0 and 1 to represent α. 1 – α represents the desired probability of accepting a lot at the AQL.
  6. In Consumer’s risk (Beta), enter a value between 0 and 1 – α to represent β. β represents the desired probability of accepting a lot at the RQL.
  7. In Lower spec, enter the lower specification limit. You must enter at least one specification limit.
  8. In Upper spec, enter the upper specification limit. You must enter at least one specification limit.
  9. Optional: In Historical standard deviation, enter the known standard deviation of your process. Use this option when you have collected enough data over time to state with confidence what the process standard deviation is.
  10. Optional: In Lot size, enter a number to represent the lot size or batch size of the entire shipment that you will accept or reject. You don't need to specify a lot size if you specify the AQL, RQL, and alpha and beta risks. However, Minitab requires the lot size to calculate the AOQ curve and the ATI curve.

Compare User Defined Sampling Plans

Complete the following steps to compare multiple sampling plans to determine the effects of varying sample size or acceptance criteria. For example, compare your current sampling plans to competing plans.
  1. From the drop-down, select Compare User Defined Sampling Plans.
  2. In Units for quality levels, select Percent defective, Proportion defective, or Defectives per million to represent the level of defectives in the process.
  3. In Acceptable quality level (AQL), enter a number to represent the highest defective rate from a supplier's process that is considered acceptable. You want to design a sampling plan that accepts a particular lot of product at the AQL most of the time.
    Note

    The AQL must be less than the RQL.

  4. In Rejectable quality level (RQL or LTPD), enter a number to represent the highest defective rate that the consumer is willing to tolerate in an individual lot. You want to design a sampling plan that rejects a particular lot of product at the RQL most of the time.
    Note

    The RQL must be greater than the AQL.

  5. In Sample sizes, specify the sample sizes that you want to compare in multiple sampling plans. In Critical distances (k values), specify the critical distances that you want to compare in multiple sampling plans.
    • Specify one sample size and several critical distances to consider the effect of varying critical distances.
    • Specify multiple sample sizes with just one critical distances to consider the effect of varying sample size.
    • Specify combinations of sample size and critical distance to consider specific paired combinations. Use the same number of sample sizes and critical distances.
  6. Optional: In Lot size, enter a number to represent the lot size or batch size of the entire shipment that you will accept or reject. You don't need to specify a lot size if you specify the AQL, RQL, and alpha and beta risks. However, Minitab requires the lot size to calculate the AOQ curve and the ATI curve.
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