st: pweight + aweight, double weights

[Jochen Späth <jochen.spaeth@iaw.edu>]

Dear Statalisters,

I have a question about weights, especially about "double weights".

I have micro-data on firms containing information about their investment behaviour (amounts) for several years. I then went on to calculate the firms' individual (discrete) growth rates of investment, i.e.

rate_t = (inv_t - inv_t-1) / inv_t-1

and wish to use these individual growth rates to calculate average growth rates for, say, economic sectors. Thereby, I'd like to attach an aweight to the -tabstat-, -table- or other suitable command, such that firms with higher investments in t-1 contribute a higher share to the average growth rate. This is, of course, straightforward in Stata. 

However, since I have sampled data I need to attach to this operation also a pweight to get information for the population instead of the sample.

Can I calculate the average growth rates from the individual ones or do I need to -collapse- or -table, replace- my data? It seems that -svyset- could be what I am looking for, but it seems rather complicated. Is there a way to avoid the -svyset- command and to go on with simple -tabstat- or alike instead?

Best,
Jochen

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