[R] mixed effects with nlme

[Spencer Graves]

1.  Have you reviewed Pinhiero and Bates (2000) Mixed Effects Models in 
S and S-Plus (Springer)?  I think the answer is there. 

2.  Observing the philosophy that a quick response that may contain an 
error is often better than a perfect but late response, I will offer a 
suggestion I have not checked:  Have you considered "random = 
~1+A+B|subj"? 

hope this helps.  spencer graves

Manuel Ato Garcia wrote:

>Dear R users:
>
> I have some difficulties analizing data with mixed effects NLME and the
>last version of R. More concretely, I have a repeated measures design with
>a single group and 2 experimental factors (say A and B) and my interest is
>to compare additive and nonadditive models. 
>
>   suj  rv    A       B
>1   s1   4   a1      b1
>2   s1   5   a1      b2
>3   s1   7   a1      b3
>4   s1   1   a2      b1
>5   s1   4   a2      b2
>6   s1   2   a2      b3
>7   s2   6   a1      b1
>8   s2   8   a1      b2
>9   s2  10   a1      b3
>10  s2   3   a2      b1
>11  s2   6   a2      b2
>12  s2   6   a2      b3
>13  s3   1   a1      b1
>14  s3   6   a1      b2
>15  s3   5   a1      b3
>16  s3   3   a2      b1
>17  s3   5   a2      b2
>18  s3   4   a2      b3
>19  s4   2   a1      b1
>20  s4  10   a1      b2
>21  s4  12   a1      b3
>22  s4   1   a2      b1
>23  s4   4   a2      b2
>24  s4   7   a2      b3
>25  s5   5   a1      b1
>26  s5  10   a1      b2
>27  s5  10   a1      b3
>28  s5   5   a2      b1
>29  s5   6   a2      b2
>30  s5   5   a2      b3
>31  s6   1   a1      b1
>32  s6   7   a1      b2
>33  s6   8   a1      b3
>34  s6   2   a2      b1
>35  s6   8   a2      b2
>36  s6   7   a2      b3
>
>It is very easy to fit these data with base R function AOV:
>
>NonAdditive model:
> aov(rv ~ A*B + Error(suj+suj/A+suj/B)
>
>Additive model:
> aov(rv ~ A*B + Error(suj)
>
>and also easy with SAS MIXED (I missed some obvious lines):
>
>NonAdditive model
> model vr = A B A*B;
> random suj A*suj B*suj;
> repeated / type=cs subj=suj;
>
>Additive model;
> model vr = A B A*B /ddfm=satterth;
> repeated / type=cs subj=suj;
> 
>Using LME I do not find any problems to fit the additive model with
>
> lme(vr~A*B, random=~1|suj, cor=corCompSymm())
>
>but I have found some difficulties fitting the nonadditive model.
>
> Can anyone help me?
> 
> Thanks in advance.
>
>	Manuel Ato
>	Dpto. Psic.Básica y Metodología
>	Apartado 4021
>	30080 MURCIA (Spain)
>	e-mail: matogar at um.es
>
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