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Hi 
I have only what you saw but my guess is as follows:

(1) Start with a vector a which gives the analytic weights, and n from
the sample.
(2) Generate a vector w = a/sum(a) , which is normalized to sum to 1.
(3) Generate a vector f = n*w, which has the weighting structure of
vector a, but is rescaled to sum to n and thus can be used as if they
were frequencies.
-----------------------------
On Mon, Oct 29, 2012 at 4:47 PM, Rita Luk <Rita.Luk@camh.ca> wrote:
> Hi Statalist,
>
> Where can I find the computation detail of analytical weights (aweight) ?
>
> In User guide 20.22.2, it says : If you specify aweights, they are: 1. Normalized to sum to N and then    2. Insert in the ... as fweights.
>
> What does it mean (in formula) to normalize the weight to sum to N?  Where can I find the formula for the normalization.
>
> I am working on point estimates of descriptive statisitcs (mean, median and histogram) using survey data and not concern about the variance at the moment. In particular, I want to  use non-svy commands with weights (let's leave the svy commands for now). I read comments from Steven Joel Hirsch Samuels and Austin Nichols and know that I will arrive at same weighted mean,median or histogram using either of the following 2 methods:
>
>        Suppose I have a survey data set with sampling  weight variable wtpp (the sum of wtpp over the entire sample equals the total population of the target population)
> 1.  converted sampling wt to integer and use as freq weight:  gen double myfw=round(wtpp*100),  then tabstat xvar [fw=myfw], s(mean median)
> 2.  Use aweight :  tabstat xvar [aw=wtpp], s(mean median)
>
> I know these methods give same estimates. But do why they give same estimates? Hence my question on the formula of normalization of weight given wtpp?
>
> I appreciate if any one can help me on this.
>
>
> Rita Luk|University of Toronto|33 Russell St. T5. Toronto,ON. M5S2S1. Canada|T: (416) 535-8501 x4727

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