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#### nonlinear best-fit line

```Good afternoon,

I am having trouble trying to figure out how to fit a nonlinear best fit
line to my data in SAS.  Any help would be greatly appreciated.

Regards,

Ligia
``` 0 2/18/2009 10:38:24 PM comp.soft-sys.sas  142828 articles. 3 followers. 0 Replies 372 Views Similar Articles

[PageSpeed] 24 Similar Artilces:

Re: nonlinear best-fit line
> -----Original Message----- > From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On > Behalf Of Ligia Buia > Sent: Wednesday, February 18, 2009 2:38 PM > To: SAS-L@LISTSERV.UGA.EDU > Subject: nonlinear best-fit line > > Good afternoon, > > I am having trouble trying to figure out how to fit a > nonlinear best fit > line to my data in SAS. Any help would be greatly appreciated. > > Regards, > > Ligia > > I think you will need to provide more information to get any useful advice. There are ways to do nonlinear estimation in a variety of contexts. You can also compute a fit for curvilinear data using linear regression techniques. So can you tell us what your data look like, and what the context is for this project? Dan Daniel J. Nordlund Washington State Department of Social and Health Services Planning, Performance, and Accountability Research and Data Analysis Division Olympia, WA 98504-5204 ...

Re: nonlinear best-fit line #2
I am looking at the values of a biological marker since time of disease diagnosis. Each point on my scatterplot represents a different person, but the time since disease diagnosis at which the lab was drawn varies (with most points occurring within 4 months of diagnosis). I think there might be a "dip" in values at some point and a linear, straight best fit line is obviously obscuring that. I would like to plot a best fit line that minimizes my residuals at each point in time. And also, look at a trend test statistic. Hope that makes it more clear... Thank you for your time. On Wed, Feb 18, 2009 at 6:30 PM, Nordlund, Dan (DSHS/RDA) < NordlDJ@dshs.wa.gov> wrote: > > -----Original Message----- > > From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On > > Behalf Of Ligia Buia > > Sent: Wednesday, February 18, 2009 2:38 PM > > To: SAS-L@LISTSERV.UGA.EDU > > Subject: nonlinear best-fit line > > > > Good afternoon, > > > > I am having trouble trying to figure out how to fit a > > nonlinear best fit > > line to my data in SAS. Any help would be greatly appreciated. > > > > Regards, > > > > Ligia > > > > > I think you will need to provide more information to get any useful advice. > There are ways to do nonlinear estimation in a variety of contexts. You > can also compute a fit for curvilinear data using linear regression > technique...

Best fit line for an exponential line
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Hello, I have a problem that is puzzling me for very long.I got this problem of fitting in 80 over text files and within each txt file,it contains about 120 datas.I want to from these datas generate a best fit line to cut through all these points.The program I am now using is Matlab.Please help and reply asap,as I need the info urgently. Thanks. In article <a488ubsdofj7@legacy>, kellyblue19@yahoo.com (Eid) writes: >Hello, > I have a problem that is puzzling me for very long.I got this >problem of fitting in 80 over text files and within each t...

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Once again: nonlinear fitting
Hi all, i want to do an exponential fit using gnuplot. I am aware that it is an art ;-) and i studied the info source as well as this newsgroup. But i'm still not understanding what's happening :-( I have a set of data 828.281 6.990E-07 828.373 2.357E-04 829.182 3.106E-02 835.662 1.899E-02 857.601 6.479E-01 865.474 4.724E+00 which is not really superb for an exponential fit but i have to try. So i tried the following a = 1E-50 b = 7.42 L(x) = a*exp(x/b) # FIT_LIMIT = 1e-100 # FIT_MAXITER = 0 fit L(x) 'L.dat' via a,b plot 'L.dat', L(x) First i guessed a set of initial values which i check by plotting the function. If i then try to fit to achieve a better result. The iteration ends after one step: Iteration 0 WSSR : 22.6854 delta(WSSR)/WSSR : 0 delta(WSSR) : 0 limit for stopping : 1e-100 lambda : 1.60359e+50 initial set of free parameter values a = 1e-50 b = 7.42 / Iteration 1 WSSR : 22.6453 delta(WSSR)/WSSR : -0.0017734 delta(WSSR) : -0.0401591 limit for stopping : 1e-100 lambda : 1.60359e+49 resultant parameter values a = 1.77558e-50 b = 7.42 After 1 iterations the fit converged. final sum of squares of residuals : 22.6453 rel. change during last iteration : -0.0017734 degrees of freedom (ndf) : 4 rms of residuals (stdfit) = sqrt(WSSR/ndf...

Nonlinear Fit
I am trying to do a nonlinear fit of a function that contains a numerical integration. My problem is that when I call the nonlinear fit, it tries to evaluate within the nonlinear fit call. For example: Test=Function[{x1,a1}, NIntegrate[a*x^3,{x,0,100}] ]; NonlinearFit[data,Test[x,a],x,{a,0,1}] Here I have a variable x and a parameter a. This would return an NIntegrate error saying that 'NIntegrate is not numerical at x={50.}' because there is an unknown, a, in the integration. It tries this a couple times and then shuts off the functioning of NIntegrat...

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Any help would be highly appreciated. I have two sets of data points, x = [........] and y = [............]. When I plot the y vs x graph, I get a plot similar to the exponential plot. However, I am trying to fit this data set through all the different possible types of fit and not just exponential fit to select the best type fit, similar to what can be done using cftool, but I want to implement it using code in MatLab. I am doing this to find the best fit to my set of data (y vs x) and get the fit coefficients; i want to use all different types of fit, so in case I do change my data (whic...

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