# [R] errors with lme4

Alessio Unisi franceschi6 at unisi.it
Mon Nov 21 18:20:26 CET 2011

```Dear list,
i'm a new R user, so I apologize if the topic is already being addressed
by some other user.

I'm trying to determine if the reproductive success of a species of bird
is related to a list of covariates.

These are the covariates:
§    elev: elevation of nest (meters)
§    seadist: distance from the sea (meters)
§    meanterranova: records of temperature
§    minpengS1: records of temperature
§    wchillpengS1: records of temperature
§    minpengS2: records of temperature
§    wchillpengS2: records of temperature
§    nnd: nearest neighbour distance
§    npd: nearest penguin distance
§    eggs: numbers of eggs
§    lay: laying date (julian calendar)
§    hatch: hatching date (julian calendar)
I have some NAs in the data.

I want to test the model with all the variable then i want to remove
some, but the ideal model:
GLM.1 <-lmer(fledgesucc ~ +lay +hatch +elev +seadist +nnd +npd
+meanterranova +minpengS1 +minpengS2 +wchillpengS1 +wchillpengS2
+(1|territory), family=binomial(logit), data=fledge)

doesn't work because of these errors:
'Warning message: In mer_finalize(ans) : gr cannot be computed at
initial par (65)'.
"matrix is not symmetric [1,2]"

If i delete one or more of the T records (i.e. minpengS2 +wchillpengS2)
the model works...below and example:

GLM.16 <-lmer(fledgesucc ~ lay +hatch +elev +seadist +nnd +npd
+meanterranova +minpengS1 +(1|territory), family=binomial(logit),
data=fledge)

> summary(GLM.16)
Generalized linear mixed model fit by the Laplace approximation
Formula: fledgesucc ~ lay + hatch + elev + seadist + nnd + npd +
meanterranova +      minpengS1 + (1 | territory)
Data: fledge
AIC   BIC logLik deviance
174 204.2    -77      154
Random effects:
Groups    Name        Variance Std.Dev.
territory (Intercept) 0.54308  0.73694
Number of obs: 152, groups: territory, 96

Fixed effects:
Estimate Std. Error z value Pr(>|z|)
(Intercept)   14.136846  14.510089   0.974    0.330
lay           -0.007642   0.267913  -0.028    0.977
hatch         -0.025947   0.267318  -0.097    0.923
elev           0.007481   0.027765   0.270    0.788
nnd           -0.035535   0.026504  -1.341    0.180
npd            0.003788   0.005521   0.686    0.493
meanterranova  1.242570   1.426158   0.871    0.384
minpengS1     -0.399852   0.418722  -0.955    0.340

Correlation of Fixed Effects:
(Intr) lay    hatch  elev   seadst nnd    npd    mntrrn
lay          0.411
hatch       -0.515 -0.993
elev        -0.015  0.141 -0.135
nnd         -0.061  0.066 -0.059 -0.020  0.231
npd          0.033 -0.108  0.100  0.298 -0.498 -0.338
meanterranv  0.459 -0.118  0.075 -0.061  0.014 -0.048  0.130
minpengS1   -0.540  0.015  0.035  0.032  0.000  0.039 -0.086 -0.970

I've attached an example of my dataset only 15 rows just to see the

regards

--
Alessio Franceschi
Phd student
Dipartimento di Scienze Ambientali "G. Sarfatti"
Università di Siena
Via P.A. Mattioli, 8  - 53100 Siena (Italy)
Cell. +393384431806
email: franceschi6 at unisi.it; alfranceschi at alice.it

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