topic Re: Fit special for a Polynomial fit in Discussions

Fit special for a Polynomial fit

shampton82 — Fri, 08 Nov 2024 21:33:28 GMT

Am I missing something when trying to fit a Polynomial from a previous fit?

It appears I can put in the linear term but not the squared term (or any of the higher order terms). Is there something special I need to do or would this be a wish list item? Seems like as you select a high ordered fit then more input boxes would appear for you to enter the values into.

Thanks for any input

Steve

Re: Fit special for a Polynomial fit

Dan_Obermiller — Sat, 09 Nov 2024 00:59:37 GMT

This seems like it may be a good wish list item, as I am not aware of any way to constrain the squared term from this platform.

However, there are some ways you could do this. If you want to "fit" the specified model you could use Nonlinear Fit, where you enter the parameters and "lock" them before running the fit. That will give you all of the summary statistics for the fit.

If you just want a visual of how it fits, you could add a formula column to your table with your known model. You could then use Graph Builder to plot your Y versus X, but then add the formula column as an additional Y. This will plot the model along with the original data to see the fit.

There are likely other ways to do it, but hopefully one of these approaches will work for you.

Re: Fit special for a Polynomial fit

shampton82 — Sat, 09 Nov 2024 01:49:04 GMT

Thanks @Dan_Obermiller !

Thats why JMP is so awesome, so many ways to accomplish a goal. I'll check out the Nonlinear option as I don't play around with it that much and would be fun to learn something new but the formula option will get me what I need in the short term. Now off to the wish list page......

Have a great weekend!

Steve