process capability difference expected and observed

[#1]

Hello,

could someone explain me what is the difference in process capability report between Observed and expected?

I imagine there is a modeling behind the expected value but cannot find in JMP help nor figure out.

thank you !

[#2]

The expected percentages are what you would expect to be outside, below the LSL, or above the USL based on the distribution chosen (by default, the distribution is normal).  So you would fit a normal distribution (or whatever distribution you chose) to the data and calculate these percentages from that.  The observed percentages are based on the actual data.  So this would be the actual percentage outside, below LSL, and above USL.

[#3]

Tonya,

thank you very much .... I was not thinking about the normal distribution modeling!

Perfect answer and so quick. You made my day!!