multinomRob - error message

Hi,

I would like to use the multinomRob function to test election results.
However, depending on which independent variables I include and how many
categories I have in the dependent variable, the model cannot be estimated.

My data look like this (there are 68 observations):

head(database)

RESTE09 GAUCHE09 PDC09 PLR09 UDC09 MCG09 RESTE05 GAUCHE05 PDC05
D1 1455 5931 4726 7283 3611 5179 0.04487642 0.1707559 0.27561790
D2 1736 10548 6905 27660 5430 5360 0.04487109 0.1797425 0.13782229
D3 4208 12452 1721 8210 3179 8960 0.18580836 0.3218897 0.05659316
D4 2182 9208 7288 10654 2951 5205 0.08227831 0.2591124 0.19605699
D5 6129 13909 12691 15560 3129 12551 0.10438878 0.2362780 0.23772964
D6 3027 13517 4702 17899 5299 5758 0.10507522 0.2034102 0.07564233
PLR05 UDC05 MCG05 dim1 dim2 dim3
D1 0.3006495 0.08555836 0.12254194 0.4327918 -0.37563170 0.23139759
D2 0.4879385 0.09903729 0.05058832 1.2723817 0.03128996 -0.10629471
D3 0.2296300 0.07822276 0.12785602 -0.8002237 -0.12194377 0.18147181
D4 0.3051325 0.06789533 0.08952449 0.4321835 0.11445829 0.24636903
D5 0.2811336 0.06624300 0.07422700 0.2560408 0.07019505 0.05611872
D6 0.4186317 0.10281440 0.09442613 0.4487914 -0.15539599 -0.04779844



I defined the model as follows:

mnr<-multinomRob(list(

+ GAUCHE09~GAUCHE05+dim1+dim2+dim3,
+ PDC09~PDC05+dim1+dim2+dim3,
+ PLR09~PLR05+dim1+dim2+dim3,
+ UDC09~UDC05+dim1+dim2+dim3,
+ MCG09~MCG05+dim1+dim2+dim3,
+ RESTE09~0),database,print.level=0)


And the error message is:

Error in multinomT.foo$se$beta : $ operator is invalid for atomic vectors
In addition: There were 11 warnings (use warnings() to see them)

warnings()

Warning messages:
1: In optim(param, fn = mt.dev, method = method, control = control, ... :
unknown names in control: tol
2: In fn(par, ...) : value out of range in 'lgamma'
3: In fn(par, ...) : value out of range in 'lgamma'
4: In fn(par, ...) : value out of range in 'lgamma'
5: In fn(par, ...) : value out of range in 'lgamma'
6: In fn(par, ...) : value out of range in 'lgamma'
7: In fn(par, ...) : value out of range in 'lgamma'
8: In fn(par, ...) : value out of range in 'lgamma'
9: In fn(par, ...) : value out of range in 'lgamma'
10: In fn(par, ...) : value out of range in 'lgamma'
11: In fn(par, ...) : value out of range in 'lgamma'


Is my model uncorrectly defined?

many thanks,

danielle martin
graduate student
department of political science
university of michigan