Hi everyone, Hope I can find a solution for this! I am fitting models to my data mostly broken-line and curvilinear plateau by Proc NLIN procedure. In some models there is a note: Convergence criterion met but a note in the log indicates a possible problem with the model! But it makes the model and gives the estimates but then I have no Std error for my estimates and no 95% confidence limits! In log I have: (I think my initial parameters are correct) DER.L not initialized or missing. It will be computed automatically. NOTE: DER.V not initialized or missing. It will be computed automatically. NOTE: DER.R not initialized or missing. It will be computed automatically. NOTE: PROC NLIN grid search time was 0: 0: 0. NOTE: Convergence criterion met. NOTE: The (approximate) Hessian is singular. NOTE: The data set WORK.PPP has 507 observations and 3 variables. And in some models I have a very big 95% confidence limits which my papers reviewer ask why!?!? Any idea and comment?? My SAS syntax for model: proc nlin data=one; *straight broken-line; parameters L=0.70 U=-1.4 R=0.80; z1=(x<R)*(R-x); model y = L + U*(z1); output out=ppp p=pred; run; proc gplot; title2 '2 linear broken lines'; goptions hpos=35 vpos=35 ftext=swiss; symbol1 v=dot c=black; symbol2 i=join v=none c=black; plot y*x pred*x/overlay; run; and results: Parameter Estimate Approx Std Error Approximate 95% Confidence Limits L 0.69 0.00949 0.6637 0.7163 U -0.9 0.2324 -1.5452 -0.2548 R 0.8 . . .
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