[R] Correlation when one variable has zero variance (polychoric?)

[Jose]

Dear John,

> I also ran the same analysis in 2005
> (what has changed in the package polycor since then, I don't know) and the
> results were different. I think back then I contrasted them with SAS
> and  they were the same.

John> I don't entirely follow this. Are you referring to the table above with 
one
John> row, more generally to table with zero marginals, or to tables in which
John> there are interior zeroes?> 

I have plenty of those tables, but I think quite a few of them have zero 
marginals (the case I posted might be a bit extreme). I have 400 observations, 
so no matter how centered the distributions are, some observations will be out 
of the center.

The results I got in 2005 cannot be reproduced now in 2007 with the same code; 
I guess this could be due to this bug you describe (maybe it was introduced 
later?). In 2007, I got many correlations has high as the one I described and I 
was wondering what the problem was. I don't have SAS available anymore so I 
cannot run the code I wrote in SAS to compare.

Where can I get the new code for polychor?

I'm in a predicament here; the data I'm analyzing are from a flight simulation 
and are extremely expensive to get, so running more experiments is out of 
question.

Any pointers as to how I could analyze this dataset? (i.e. one where there 
might be zero marginals?)

Thanks

-Jose