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Re: st: collapse and weights

From   Austin Nichols <>
Subject   Re: st: collapse and weights
Date   Mon, 26 Nov 2012 18:36:28 +0100

Tomáš Houška <>:
Your goal is a bit hard to understand from the description--are you
saying you want the sum of q and the q-weighted mean of price?
g one=1
collapse (sum) sum=one (mean) price [fweight=q], by(prod_group)

On Sun, Nov 25, 2012 at 9:44 AM, Tomáš Houška <> wrote:
> Dear Statalist,
> I have data containing weekly information on prices and quantities of
> sales of several products. These products can be divided into few
> groups and I would like to create for each group 1) an weighted
> average weekly price for the group where weight is the amounts of sale
> of each product in the group and 2) sum of sales of the products that
> belong to particular group. I will end up with average price and total
> sales for the given product group.
> But if I use
> -- collapse (sum) q (mean) price [fweight=q], by(prod_group) --
> the weights get applied both to the average and the sum, which is not
> correct. I havent been able to come up with a solution how to bracket
> the stata command. Could someone please give me some guidance?
> Thank you!
> Tomas (PhD student)

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