[Rd] How to use formulas for multivariate clustered data?

[Klaus Nordhausen]

Dear R experts,

I wrote already a couple of weeks ago but did not get any reply.  
Therefore I'll rephrase my question and hope some of you can give me  
some answers or some advice where better to look for an answer.

In general I'm looking for information on how to program functions  
using formulas in order to write a nonparametric multivariate  
regression function with possible clustering of the data.

I would assume that the formulas for my function would have the form
y1 + y2 + y3 ~ x | z
or
Y ~ x | z,

where y1, y2 and y3 are continuous response variables, or Y the matrix  
of responses and x an explaining variable and z a factor indicating  
the cluster membership.

I'm looking for general information about writing functions using  
formulas. But more concrete I would need to know what would be the  
best way to make sure that the response should be multivariate and  
numeric? What is the best way to define the hierarchical structure, is  
it the "|" or is there another, better way? How can I restrict the  
number of hierarchical levels?
And how to use in this context, the data, subset, weights and na.action
arguments?

Thanks in advance,

Klaus

-- 
Klaus Nordhausen
Researcher
Tampere School of Public Health
FIN-33014 University of Tampere

phone:	+358 3 3551 4153
fax:	+358 3 3551 4150
e-mail:	Klaus.Nordhausen at uta.fi