[R] multinomial logit discrete choice model

[DJ]

Hi,

I'm struggling trying to specify a multinomial logit discrete choice model
in R.

Any help and/or code examples appreciated.

I am specifically interested in specifying a model where no universal choice
set exists and each choice set has a variable number of alternatives (one of
which is chosen) see data below.

Many Thanks,

David

PS I have asked earlier but without reply.

Is it because:
    a. it's a stupid question
    b. It's obvious
    c. No one knows the answer


Data:
> Chosen  AttrQ   AttrW  | Choices set 1
> 0             8            0      |
> 1            20         34      |
> 0             7            2      |
>
> 0             5            3      |      set 2
> 0             3            5      |
> 1           25          18      |
> 0            4             9      |
>
> 1          30           12      |      set 3
> 0            2            4       |