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.
- From the drop-down, select Compare User Defined Sampling Plans.
- In Measurement type, select whether you count number of defectives or number of defects.
- Go / no go (defective): Use when you inspect units and record whether the product is defective or not.
- Number of defects: Use when you inspect units and record the number of defects found.
- In Units for quality levels, select the units of measure for your data.
- If you count defectives, select Percent defective, Proportion defective, or Defectives per million to represent the level of defectives in the process.
- If you count defects, select Defects per unit, Defects per hundred, or Defects per million to represent the level of defects in the process.
- In Acceptable quality level (AQL), enter a number to represent the highest defective rate or defect 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.
The AQL must be less than the RQL.
- In Rejectable quality level (RQL or LTPD), enter a number to represent the highest defective rate or defect 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.
The RQL must be greater than the AQL.
- In Sample sizes, specify the sample sizes that you want to compare in multiple sampling plans. In Acceptance numbers, specify the acceptance numbers that you want to compare in multiple sampling plans.
- Specify one sample size and several acceptance numbers to consider the effect of varying acceptance number.
- Specify multiple sample sizes with only one acceptance number to consider the effect of varying sample size.
- Specify combinations of sample size and acceptance number to consider specific paired combinations. Use the same number of sample sizes and acceptance numbers.
- 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.