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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 ______________________________________________________________________ This email has been scanned by the CAMH Email Security System. ______________________________________________________________________ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

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