This is new statistics space for me, so please excuse my ignorance.
I have some data (N=180) that isn't normally distributed (verified in Minitab, P<0.005) and I want to use the data to get a +/- 4 sigma specification limit. Basically, I want to say:
"We can expect 99.993666% of parts to have a measured dimension between DATA_LSL and DATA_USL."
None of the distributions in Minitab fit with good confidence, and so I found that sometimes you can do bootstrapping, which is something like re-sampling your data to get an idea of the uncertainty in some statistic based on 1000+ random re-samples. I think I got that right, but I may be mistaken.
Does anyone know how to bootstrap the standard deviation in Minitab? I found a macro that does it for the mean, and I can put in whatever confidence interval that I want. I think that only tells me about the mean, though, and not the standard deviation.
There are some papers that talk about bootstrapping for LSL/USL, but nothing that I can find that's an example/macro in Minitab.
Any help or advice would be greatly appreciated :)
Thanks, Adam Hartman Mechanical Engineer - Flextronics