turn on suggestions

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

Find a Community

- Home
- /
- Analytics
- /
- Stat Procs
- /
- How to estimate the parameters for nonlinear funct...

Topic Options

- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

03-22-2013 09:10 AM

Hi Guys,

I want to fit my data with the function as below:

**y=a*exp(b*x1)+c*x2+d*x3+e*x4**

**x1,x2** are continoues preditc variables,and **x3,x4** are catogory preditc variables. **a,b,c,d,e** are paramters which need to be estimated.

Which procedure will work? proc nlin works for catogory preditc variables?

Thanks.

Tomi

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

Posted in reply to TomiKong

03-22-2013 09:19 AM

If you have x3 and x4 coded as categorical, then you should be ready to use PROC NLIN. If they have not yet been coded, you will probably want to run your data through PROC GLMMOD to automatically convert categorical variables to the coded form needed for regression.

Steve Denham

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

Posted in reply to SteveDenham

03-22-2013 01:07 PM

Thanks, Steve.

I'm supposed to create dummy variables for all catogary data first and then use PROC NLIN to do regreesion, right?

Tomi

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Report Inappropriate Content

Posted in reply to TomiKong

03-22-2013 04:34 PM

Yes, you need dummy variables. If X3 has three levels, then you need two dummy variables. Using GLM-type parametrization, you would need X3_1 (where X3_1 = 1 if X3 is at level **1**, 0 otherwise) and X3_2 (where X3_2 = 1 if X3 is at level **2**, and 0 otherwise). Same for X4. This means you could have many parameters to estimate and interpret with proc nlin or proc nlmixed. It can get tricky.