[R] how to prepare my data to be used in the "survey" package

[David Remotti]

Looking for some help in using the "survey" package
I have gone through the documentation but still find problems in 
understanding how to prepare my data to be analyzed wih this package.

In particular I dont understand how to prepare the fpc data.
The documentation provides a "small survey example" where 6 variables 
are given:
stratid,psuids,weight,nh,Nh and x

My survey is a two stage stratified sampling so I have for each stratum 
the number of primary
and secondary units in the sample and in the population, and using these 
data I can prepare such
data frame, except for the last variable "x".
I cant understand what does it means and which information I have to put 
there.

A second (minor) problem is that my stratification is based on two 
variables, but it looks like it is only possible to give 1 variable as 
strata parameter.
Is it possible to give two ?

thanks in advance for any indication
David Remotti
Rome
Italy