[R] Problem with multinom ?

[Marc Girondot]

Thanks for your response.
OK, multinom() is a more logical in this context.

But similar problem occurs:

Let these data to be analyzed using classical glm with binomial error:

m   f   factor   m theo              f theo 
-Ln L model        -Ln L full          interecept 
f
10  12  1.2      0.452494473  0.547505527 
1.778835688  1.778648963    2.632455675 
-2.034882223
14  14  1.3      0.503222759  0.496777241  1.901401922  1.900820284
15  12  1.4      0.553884782  0.446115218  1.877062369  1.876909821

                                 Sum -Ln L 
5.557299979  5.556379068  Residual deviance
                                 Deviance 
11.11459996  11.11275814   0.001841823

If I try to use multinom() function to analyze 
these data, the fitted parameters are correct but 
the residual deviance not.

>  dt<-read.table('/try.txt'. header=T)
>  dt
   output factor  n
1      m    1.2 10
2      f    1.2 12
3      m    1.3 14
4      f    1.3 14
5      m    1.4 15
6      f    1.4 12
>  dt.plr <- multinom(output ~ factor. data=dt. weights=n. maxit=1000)
# weights:  3 (2 variable)
initial  value 53.372333
iter  10 value 53.115208
iter  10 value 53.115208
iter  10 value 53.115208
final  value 53.115208
converged
>  dt.plr
Call:
multinom(formula = output ~ factor. data = dt. weights = n. maxit = 1000)

Coefficients:
(Intercept)      factor
   -2.632443    2.034873

Residual Deviance: 106.2304
AIC: 110.2304

>  dt.pr1<-predict(dt.plr. . type="probs")
>  dt.pr1
         1         2         3         4         5         6
0.4524948 0.4524948 0.5032229 0.5032229 0.5538846 0.5538846

Probability for 2. 4 and 6 are not correct and 
its explain the non-correct residual deviance 
obtained in R.
Probably the problem I have is due to an 
incorrect data format... could someone help me... 
Thanks

(I know there is a simple way to analyze binomial 
data. but in fine I want to use multinom() for 5 
categories of outputs.


Thanks a lot

Marc
-- 

__________________________________________________________
Marc Girondot, Pr
Laboratoire Ecologie, Systématique et Evolution
Equipe de Conservation des Populations et des Communautés
CNRS, ENGREF et Université Paris-Sud 11 , UMR 8079
Bâtiment 362
91405 Orsay Cedex, France

Tel:  33 1 (0)1.69.15.72.30   Fax: 33 1 (0)1 69 
15 56 96   e-mail: marc.girondot at ese.u-psud.fr
Web: http://www.ese.u-psud.fr/epc/conservation/Marc.html
Skype: girondot
Fax in US: 1-425-732-6934