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st: question about standardizing
i have some doubts about standardizing rates in stata.
i've always used -dstdize-. in fact what this command does is
standardizing binomial variable, doesn't it'? variance is calculated on
lines 387-391 of the dstdize.ado file (i'm reading the file from base
distribution of stata 9), and the formula is that of a binomially
this make it suitable for standardizing *proportions*.
i've discovered recently that in stata 9 standardization is also
possible for means, with the -mean- command and the -stdize, and a new
command is available for proprtions, namely the -proportion- command. if
i understand the command -ratio- is a generalization of the previous, in
case data are aggregated.
now the question are:
1) what if i need to standardize actual rates, i.e., poisson variables?
2) what if i have a dataset for aggregated means? for example: i need
to calculate the average length of stay in hospital for a given
intervention, but i only have aggregated length of stay, for example
state age tot sub
1 65 500 50
2 65 613 57
3 65 802 75
1 75 470 40
2 75 715 37
3 75 950 60
i guess that in order to compute confidence intervals i would also need
the sums of the squares of the lengths of stay (assuming length of stay
normally distributed), am i correct? well if i had it, would it be
possible to use a stata command to produce standardized means with
thanks for any suggestion!!
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