Hi Jia, in order to test if the failing parameter estimation really has to do with wrong initial values, you could first simulate data with your mixed effects model. Just assume parameters, produce a data set with these parameters, add noise and look if you can estimate the parameters correctly with varying initial guesses.
On Tue, 2011-03-15 at 12:34 -0700, jia liu wrote: > Hi, > When I fit the mixed-effects model by lme, I got theconvergence error code = 1 > message = iteration limit reached without convergence (9). Even after I > increase the iteration numbers, it still did not work. The only way I found > to avoid the error message is to increase thenumber of iterations for the EM > algorithm, which need to be at least 1100. But the weird thing is that the > correlation between two random coefficients is always around 1, which is not > true. So I am thinking the error should be related with the improper starting > value. But I do not know how to set up my desired starting value in lme > function. Are there anybody know it? Or met the same problem with me before > and know how to avoid the error? Thank you for your help. > Bests, > Jia > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Daniel Kaschek Physikalisches Institut, Freiburg Hermann-Herder-Str. 3 79104 Freiburg Office: Westbau, 02020 Phone: +49-761-203-8531
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______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
