I have to a model
threshold = 100 -2*deltat + c1*sigma^a + c2*deltat^2 + c3*sigma^c * deltat^d
where I know 0<threshold<100 as it is in all my datapoints (https://pastebin.com/3pYiNFf1)
To do this I run the following code (and I am fully aware this approach is incredibly stupid/ridiculous but I can't think of anything better) using the nlmixed procedure with as model the binomial distribution with 100 trials, and succes chance hopefully threshold/100.
PROC NLMIXED data=BEP;
PARMS c1=-1, c2=0, c3=0, a=1, b=1, c=1, d=1;
p = (100 - 2*deltat + c1*sigma**(a) + c2*deltat**(b) + c3*sigma**(c) * deltat**(d))/100;
model threshold ~ binomial(100,p);
run;
However when running this I get no output and the log says
Run NLMIXED with option trace to get debug info. The problem is related to cases where sigma=0. NLMIXED is trying to take the log of sigma and fails. You can get convergence by replacing sigma=0 by sigma=0.01.
With sigma=0.01, the results indicate that your model is overparameterized, likely because of the two terms involving sigma with different exponents. Just a guess.
Run NLMIXED with option trace to get debug info. The problem is related to cases where sigma=0. NLMIXED is trying to take the log of sigma and fails. You can get convergence by replacing sigma=0 by sigma=0.01.
With sigma=0.01, the results indicate that your model is overparameterized, likely because of the two terms involving sigma with different exponents. Just a guess.
Are you ready for the spotlight? We're accepting content ideas for SAS Innovate 2025 to be held May 6-9 in Orlando, FL. The call is open until September 25. Read more here about why you should contribute and what is in it for you!
ANOVA, or Analysis Of Variance, is used to compare the averages or means of two or more populations to better understand how they differ. Watch this tutorial for more.
Find more tutorials on the SAS Users YouTube channel.