topic Re: How to write your own non-linear model in Discussions

How to write your own non-linear model

ukhandurrani — Sat, 10 Jun 2023 20:45:39 GMT

I need to analyze my data using the Von Bertalanffy Growth function to my data (age vs Length). But I couldn’t figure out where and how to write my own non-linear regression model. Need help. My model is:

a*(1-exp(-(b*(age-c))))

Re: How to write your own non-linear model

dale_lehman — Tue, 22 Jun 2021 11:42:25 GMT

You can use the nonlinear platform (found under specialized modeling). a, b, and c should be entered as parameters (you need to supply initial values) and the platform will fit your model to your data - if it converges. If not, you might have to change your initial guesses for the parameters. If you haven't done this before, instead of entering variables in your formula, change the drop down menu from Table Variables to parameters.

Re: How to write your own non-linear model

ukhandurrani — Tue, 22 Jun 2021 11:57:33 GMT

Thanks for the reply. Could you please check the attached screenshots; I did not get any results :(

Re: How to write your own non-linear model

ukhandurrani — Tue, 22 Jun 2021 12:13:43 GMT

Please have a look at this too:

Re: How to write your own non-linear model

dale_lehman — Tue, 22 Jun 2021 12:55:17 GMT

In the nonlinear launch, you need to put your predictor formula as "predictor" not the age variable.

Re: How to write your own non-linear model

ukhandurrani — Tue, 22 Jun 2021 13:39:55 GMT

Hi
I followed these steps: Analyze => Nonlinear => Model Library => Gompertz model (it is similar to my equation) => Selected Y and X from my data => then in my spreadsheet a new column is added and by double clicking on it a new windows open for editing formula.

But I did not get any output results just like JMP own nonlinear regression :(

Re: How to write your own non-linear model

ukhandurrani — Tue, 22 Jun 2021 13:50:17 GMT

Hi again,
I want to get output results similar to the attached screenshot from my equation (Von bertalanffy equation). Thanks

Re: How to write your own non-linear model

Jeff_Perkinson — Tue, 22 Jun 2021 15:58:40 GMT

Take a look at the documentation for the Nonlinear platform. The first section walks through an example to show exactly how to do this.

In short, after creating the column with your formula and parameters you put that column in the X, Predictor Role and your response column in the Y role.

The example you've given is from the Fit Curve platform. The output from Nonlinear is similar, though not exactly the same.

Re: How to write your own non-linear model

Kevin_Anderson — Tue, 22 Jun 2021 16:55:43 GMT

Hi, ukhandurrani!

If you include a data table with your request for help (either yours or an example), the helpful responses you receive may be more implementable for you.

Kevin

Re: How to write your own non-linear model

ukhandurrani — Tue, 22 Jun 2021 16:59:16 GMT

Thanks for the hints. It works and got the results. But I did not get "Summary of Fit". I also need to get AIC, BIC, R2 etc. to check my model fitness. Thanks once again for the hints.

Re: How to write your own non-linear model

Chirag — Thu, 06 Jul 2023 08:13:22 GMT

Dear sir, But, how to get the prediction model and other results like the goodness of fit criteria result like AIC, AICC, BIC, SSE, MSE, RMSE, R-Square, parameter estimate + SE, wald chi-square p-value, upper and lower confidence intervals,

as well as predicted and residual values, Correlation and Covariance of Estimates