Minitab calculates an accept or reject decision based on your measurements from sampled items and the criteria (sample size and critical distance) of your variables acceptance sampling plan.
First Minitab calculates the mean and standard deviation from your data (if you have not specified a historical standard deviation):
Minitab uses σ instead of s in the Z calculations when you provide a historical standard deviation.
|s||estimated standard deviation|
|σ||known standard deviation|
|L||lower specification limit|
|U||upper specification limit|