Is there any kind of "unusual" appearance, such as severe clustering? I waited as long as 20 minutes but nothing. I need odds ratios and so I need tot do a logistic regression procedure. To run a population averaged model, you would have to define individual as the subject and specify the covariance structure for each subject's multiple measurements.
PLease could you tell me what could be the problem ion that case.THank you very much.Pooja Message 3 of 18 (1,221 Views) Reply 0 Likes SteveDenham Super User Posts: 2,546 Re: If that were true, we’d want to estimate the variance among classrooms. I once had a hessian problem go away when I divided the DV by 1000. WARNING: The procedure is continuing but the validity of the model fit is questionable. https://communities.sas.com/t5/SAS-Enterprise-Guide/Proc-genmod-error/td-p/85344
Be careful here, as it can make a big difference. I tried this on my data, however, I always get the same warning: WARNING: The generalized Hessian matrix is not positive definite. When I ran both genmod and glimmix without the propensity variables they gave similar (not exactly same) results. Chapman & Hall.
The dependent variable "y" contains the individual values for each trait. COM> Date: 2015-08-01 15:47:10 Message-ID: 5875790950539706.WA.verdantsphinxgmail.com () listserv ! When this happens, you need to respecify the random parts of the model. What does the cross-tabulation for this endpoint reveal?
Unfortunately, I think the errors that are currently occurring will still occur under these options, so perhaps some others can help out on this.Steve Denham Message 4 of 18 (1,221 Views) One simple solution is to check the scaling of your predictor variables. Or you may need to use a simpler covariance structure with fewer unique parameters. https://communities.sas.com/t5/SAS-Statistical-Procedures/Proc-genmod-how-to-resolve-error-messages/td-p/33607 Any help would be great.
One example is the following, where n is the first drug, d the second and cve is the event of interest: data tt; input n d cve freq; datalines; 1 1 any ideas? Patients (ptno) have multiple visit sequentially indicated by the variable visitindex. I don't even look at them.
Reply With Quote + Reply to Thread Tweet « Significant interaction | few replicates with several categories and subgroups » Tags for this Thread proc genmod View Tag Cloud read this article Most of the variables are binary, however when I add a variable with more then two levels I get the error statement concerning the Generalized Hessian Matrix (I believe it says Warning: The Generalized Hessian Matrix Is Not Positive Definite. Iteration Will Be Terminated. Without getting into the math, a matrix can only be positive definite if the entries on the main diagonal are non-zero and positive. I tried PROC GENMOD and PROC \ GLIMMIX but they both produced errors.
If excluding the propensity variables does not work, then we are dealing with a whole other set of problems.Steve DenhamSteve Denham Message 6 of 18 (1,221 Views) Reply 0 Likes Pooja My dependent variable is the number of healthcare visits in ADHD patients and the independent variables include age, sex, ethnicity, physician specialty, confirmed diagnosis of ADHD in pre-index period, number and You're better off computing the intraclass correlation. I then added in one variable at a time and the convergence problem only arises when I add the variable nothvst1.
Showing results for Search instead for Do you mean Find a Community Communities Welcome Getting Started Community Memo Community Matters Community Suggestion Box Have Your Say SAS Programming Base SAS Programming This is the model I am using : proc mixed data= mmlw34 covtest asycov ; class trait family Block sample; model y = trait block; random trait /type=un sub=family g gcorr; Do you have enough data? Should help with understanding http://www.theanalysisfactor.com/wacky-hessian-matrix/ Feb 22, 2015 Francisco Babinec · Instituto Nacional de Tecnología Agropecuaria Paper 332-2012 : Tips and Strategies for Mixed Modeling with SAS/STAT ® Procedures (http://support.sas.com/resources/papers/proceedings12/332-2012.pdf), and
And fyi, West, Welch, and Galecki's Linear Mixed Models book has a nice explanation about the Hessian matrix warning, if you'd like more info. I have checked the covariance parameters and they are positive and not near 0. Sage Publications.
It may mean you need to remove a random effect. What do I do about it? Advanced Search Forum Statistical Research Biostatistics GEE model with Error " The generalized Hessian matrix is not positive definite" Tweet Welcome to Talk Stats! The problem with this variable occurs in both genmod and glimmix.
I bolded a couple of changes that might help, but I would not be surprised if this took several hours, and you got the message that it had not converged. Gave no errors but did not run. Thank you very much! Then the distribution should be multinomial, with a cumulative logit link.
I obtain the covariance parameters, the G matrix, the G correlation matrix and the asymptotic covariance matrix. Also, I am using proc Genmod.