st: stptime command issue

[Elisabetta Petracci <elisabetta.petracci@gmail.com>]

Dear all,

*I am running the example 2 (page 338) of the st.pdf Stata 11 manual to
calculate age-specific incidence rates.
*I am using this dataset*

use http://www.stata-press.com/data/r11/diet

*I set the dataset*

stset dox, origin(time dob) enter(time doe) id(id)
scale(365.25)fail(fail==1 3 13)

*dox=date of exit from the study

*doe=date of entry

*dob= date of birth

*Then I run:*

stptime, per(1000) at(40(10)70) trim

*At this point I wanted to check by hand the calculation of person-time at
*least for the first age group.

*I don't get 907 person-time for the first age-group. Shouldn't I take those
subjects who have _t<=50 and then sum over the _t within this interval?*

Many thanks.

Elisabetta
*
*   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/