On Monday, Cristian asked for references for the command -stir-.
As Richard said in his response, -stir- calls -ir-. So, all that -stir-
is really doing for us, is creating a datset that -ir- can work with. In
other words, it creates var_case, var_exposed and _var_time variables,
as follows:
clear
webuse page2
stset
gen var_case=_d
gen var_exposed=(group==2)
gen var_time = _t - _t0
ir var_cas var_exposed var_time
stir group
You may feel like -stir- isn't doing much for you after looking at this
example, but -ir- only wants its variables in certain formats,
for example exposed must be 0/1, and -stir- can take care of
things like changing strings to 0/1, etc.
A good reference for the formulas is Rothman "Modern Epidemiology".
In the 1986 edition, the relevant page numbers are:
-incidence rate 164-172
-attibutable fraction 38-39
-midp 155
In the version 8 [ST] manual, this is described on page 61-62.
In the version 7, look on page 482-483 in [R] epitab.
--May
[email protected]
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