Re: st: Standard error of a ratio of two random variables

[Steven Samuels <sjhsamuels@earthlink.net>]

Sergiy, Could you please give some details of the study that you are  
analyzing? Is it a multi-stage sample?  For the -ratio- commands to  
work, X and Y must be measured on each observation.  What are the  
observations?  In particular, I don't understand what you mean by  
"domains", so I'm not sure how to answer your question about  
"domains... that do not overlap."

-Steve

On Tue, Jan 13, 2009 at 11:35 AM, Sergiy Radyakin
<serjradyakin@gmail.com> wrote:
> Dear All,
>
> thank you for your responses. Austin's solution to remove rho helped a
> lot, but I am a bit confused with the other alternative that he
> proposed, namely "keep the rho, but divide by N". What would N be in
> the case, where the mean of X is be computed on one domain, and mean
> of Y on another? (e.g. because of the missings). For example, X is
> income, and Y is family size, and I were interested in per capita
> income, but income was less often reported than family size. My
> observation is that Stata stops with error "no observations" in case
> when domains of X and Y do not overlap at all, but there is nothing in
> the formula that prevents me from computing (approx) moments of X/Y in
> this case. Should I restrict computations to the common domain where
> both X and Y are not missing for some reason?
>
> Alan, thank you for the comments regarding not existance of moments in
> case the the X and Y are N(0,s2). In my case the expectations of X and
> Y are guaranteed to be non-zero as they are the numbers of people with
> non-exotic characteristics (like attending primary school).
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/