Sample Size

Question

Hi,

I want to know how many samples I need to run to pass my spec (fail of 2%). I know the fail rate which is .6%. How would I do this in JMP?

In other words, a lot passes if it has less than 2% failing parts. How many samples do I need to run to be confident I will pass.

Thank you,

Rami

cwillden · Answer

Are your data pass/fail or do you have continuous measurements that are compared to a spec? If it's the former, you'll want to use the One Sample Proportion calculator, and you will need a lot of samples (hundreds).  If your data are continuous, you can probably make the same quality claim with far fewer samples.  There are quite a few ways to do with continuous data.  One approach would be to calculate a 98% tolerance limit and show that it is contained within your spec(s).

Mark_Bailey · Answer

You will find Sample Size and Power in the DOE menu. This command has moved so the exact location depends on the version. It is currently in the Evaluate Design sub-menu.

See Help > Books > Design of Experiments. There is a chapter about this platform and it shows examples that you can adapt to your problem.