[R] what does this warnings mean? and what should I do?
Spencer Graves
spencer.graves at pdf.com
Sat Dec 17 01:13:35 CET 2005
You actually received two different warning messages. The first 8
warnings read, "optim or nlminb returned message false convergence (8)",
and the other 3 say, "... returned message singular convergence". The
function "lmer" uses a nonlinear optimizer (either "optim" or "nlminb")
to minimize an objective function. The first message says that the
nonlinear optimizer was still reducing the objective function when it
reached an iteration limit. If this were the only problem, you might
consider increasing the iteration limits, maxIter, msMaxIter, niterEM
and PQLmaxIt. However, the "singular convergence" message says that the
estimated variance-covariance matrix of the observations became singular.
Looking now at your output, I notice that "Corr" between
"(Intercept)" and "trust.cz1" for the "Random Effects" "commid" is
1.000. This says that the structure of your data are not adequate to
allow you to distinguish between random effects for "(Intercept)" and
"trust.cz1" for "commid", while simultaneously estimating all the fixed
effects you have in the model.
If I were you, I'd start be deleting all the terms from the model
that don't have a "Signif. code" beside it in the table of "Fixed
effects" and then refit the smaller model, preferably also using
'method="AGQ"'. If I still get the same message from trying to fit the
reduced model, I would conclude that the data are not adequate to
distinguish between "(Intercept)" and "trust.cz1" for "commid". I would
then delete "trust.cz1" from the model and go from there.
hope this helps.
spencer graves
ronggui wrote:
> I use lmer to fit a mixed effect model.It give some warnings.what does this warnings mean? and what should I do?
>
>
>>(fm2.mlm <- lmer(qd ~ edu + jiankang + peixun +hunyin + cadcj +
age + age2 + sex + dangyuan + Comp.1 + Comp.2+trust.cz1 +
(trust.cz1|commid), data = individual,na.action =
"na.exclude",family="quasibinomial"))
>
> Generalized linear mixed model fit using PQL
> Formula: qd ~ edu + jiankang + peixun + hunyin + cadcj + age + age2 + sex + dangyuan + Comp.1 + Comp.2 + trust.cz1 + (trust.cz1 | commid)
> Data: individual
> Family: quasibinomial(logit link)
> AIC BIC logLik deviance
> 736.7059 821.8267 -349.3529 698.7059
> Random effects:
> Groups Name Variance Std.Dev. Corr
> commid (Intercept) 1.56413 1.25065
> trust.cz1 0.17922 0.42334 1.000
> Residual 0.89728 0.94725
> # of obs: 652, groups: commid, 39
>
> Fixed effects:
> Estimate Std. Error DF t value Pr(>|t|)
> (Intercept) -1.6115e-01 6.7997e-01 637 -0.2370 0.81274
> edu -5.2585e-02 4.1048e-02 637 -1.2810 0.20064
> jiankang -9.8243e-01 4.4645e-01 637 -2.2005 0.02813 *
> peixun -4.6307e-01 2.6397e-01 637 -1.7542 0.07988 .
> hunyin -1.2255e-02 2.8151e-01 637 -0.0435 0.96529
> hunyin -2.7726e-01 1.3846e+00 637 -0.2002 0.84136
> hunyin -2.9759e-01 8.7180e-01 637 -0.3414 0.73295
> cadcj 2.2366e-01 7.6467e-01 637 0.2925 0.77000
> age 9.3626e-02 4.0390e-02 637 2.3180 0.02076 *
> age2 -1.3095e-03 5.5104e-04 637 -2.3763 0.01778 *
> sex 3.9188e-01 1.9759e-01 637 1.9833 0.04776 *
> dangyuan -5.2558e-01 5.9091e-01 637 -0.8894 0.37410
> Comp.1 5.2463e-02 1.0309e-01 637 0.5089 0.61100
> Comp.2 -1.5048e-01 1.1435e-01 637 -1.3160 0.18863
> trust.cz1 -8.0709e-01 4.4632e-01 637 -1.8083 0.07103 .
> ---
> Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
> There were 11 warnings (use warnings() to see them)
>
>>warnings()
>
> Warning messages:
> 1: optim or nlminb returned message false convergence (8)
> in: LMEopt(x = mer, value = cv)
> 2: optim or nlminb returned message false convergence (8)
> in: LMEopt(x = mer, value = cv)
> 3: optim or nlminb returned message false convergence (8)
> in: LMEopt(x = mer, value = cv)
> 4: optim or nlminb returned message false convergence (8)
> in: LMEopt(x = mer, value = cv)
> 5: optim or nlminb returned message false convergence (8)
> in: LMEopt(x = mer, value = cv)
> 6: optim or nlminb returned message false convergence (8)
> in: LMEopt(x = mer, value = cv)
> 7: optim or nlminb returned message false convergence (8)
> in: LMEopt(x = mer, value = cv)
> 8: optim or nlminb returned message false convergence (8)
> in: LMEopt(x = mer, value = cv)
> 9: optim or nlminb returned message singular convergence (7)
> in: LMEopt(x = mer, value = cv)
> 10: optim or nlminb returned message singular convergence (7)
> in: LMEopt(x = mer, value = cv)
> 11: optim or nlminb returned message singular convergence (7)
> in: LMEopt(x = mer, value = cv)
>
>
>>version
>
> _
> platform i386-pc-mingw32
> arch i386
> os mingw32
> system i386, mingw32
> status
> major 2
> minor 2.0
> year 2005
> month 10
> day 06
> svn rev 35749
> language R
>
>
>
>
>
>
> 2005-12-14
>
> ------
> Deparment of Sociology
> Fudan University
>
> My new mail addres is ronggui.huang at gmail.com
> Blog:http://sociology.yculblog.com
>
>
>
> ------------------------------------------------------------------------
>
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--
Spencer Graves, PhD
Senior Development Engineer
PDF Solutions, Inc.
333 West San Carlos Street Suite 700
San Jose, CA 95110, USA
spencer.graves at pdf.com
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