# Statistical basis and justification while comparing / changing sampling plans

#### Mai Nguyen

##### Registered
Our factory sets sampling plan at AQL 1.0, c=0. Can anyone let me know what confident interval of AQL 1.0, c=0?
Thank you!

#### Bev D

##### Heretical Statistician
Staff member
Super Moderator
Welcome Mai.

Your question, while simple, has not easy answer. This is a complex topic that is not well understood by many. First sampling plan doesnt’ have a confidence interval. Confidence intervals are calculated after the sampling and inspection or test is complete. We need the number of defects found and the sample size adn the confidence level to calculate the interval.

Are you asking about the confidence level? For AQL plans taken from a published table, this is usually 95%. Btu we must remember that this is means (in your example) that 95% of the time when a defect rate of 1% is present, you will accept the lot.

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