Your model is too complex for the data. This gives you two options: a) simplify the model and b) get more data.
Best regards, ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance Kliniekstraat 25 1070 Anderlecht Belgium To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey 2015-06-09 21:57 GMT+02:00 li li <hannah....@gmail.com>: > Hi all, > I'd like to fit a random intercept and random slope model. In my > data, there are three groups. I want to have different random > intercept for each group but the same random slope effect for all > three groups. I used the following R command. > However, there seems to be some problem. Any suggestions? > > > > mod2 <- lmer(result ~ group*time+(0+group1+ group2 + > group3+time|lot), na.action=na.omit, data=alldata) > > > summary(mod2) > Model is not identifiable... > summary from lme4 is returned > some computational error has occurred in lmerTest > Linear mixed model fit by REML ['merModLmerTest'] > Formula: result ~ group * time + (0 + group1 + group2 + group3 + time | > lot) > Data: alldata > > REML criterion at convergence: 807.9 > > Scaled residuals: > Min 1Q Median 3Q Max > -3.0112 -0.3364 0.0425 0.2903 3.2017 > > Random effects: > Groups Name Variance Std.Dev. Corr > lot group1 0.00000 0.000 > group2 86.20156 9.284 NaN > group3 55.91479 7.478 NaN 0.06 > time 0.02855 0.169 NaN -0.99 0.10 > Residual 39.91968 6.318 > Number of obs: 119, groups: lot, 15 > > Fixed effects: > Estimate Std. Error t value > (Intercept) 100.1566 2.5108 39.89 > group group2 -2.9707 3.7490 -0.79 > group group3 -0.0717 2.8144 -0.03 > time -0.1346 0.1780 -0.76 > group group2 :time 0.1450 0.2939 0.49 > group group3:time 0.1663 0.2152 0.77 > > Warning messages: > 1: In checkConv(attr(opt, "derivs"), opt$par, ctrl = control$checkConv, : > Model failed to converge with max|grad| = 0.147314 (tol = 0.002, > component 2) > 2: In checkConv(attr(opt, "derivs"), opt$par, ctrl = control$checkConv, : > Model failed to converge: degenerate Hessian with 2 negative eigenvalues > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
