JS,
I do not think there exist a _simple_ Stata command which would help
you achieving what you are asking for. But you could try to program it
yourself. I prepared some example code to show you how I would do it.
And as always I would expect that the code can be improved or maybe
some expert knows a Stata command that can do the trick.
regards
Sebastian
Here ist the code ...
/* BEGIN EXAMPLE */
//inputting example data
clear
input str3 event str9 txt_start_date str9 txt_end_date
XYZ 11jan2004 07feb2004
ZZZ 11jan2004 08feb2004
YYY 14jan2004 22jan2004
XXX 21jan2004 13mar2004
ZZY 30jan2004 04feb2004
end
//creating numeric dates from the string variables
gen start_date = date(txt_start_date,"dmy")
gen end_date = date(txt_end_date,"dmy")
//record all levels from variable event to local macro -eventlist-
levelsof event, local(eventlist)
//initialize variables required
gen global_start=.
gen global_end=.
gen in_range=.
gen other_obs=.
tempvar tmp_oo
//begin looping over levels of event as recorded in local macro -eventlist-
quiet { //quiet mode
foreach el of local eventlist {
//copy begin of event to "global variable"
replace global_start = start_date if event == "`el'"
//copy end of event to "global variable"
replace global_end = end_date if event == "`el'"
//copy event date rangeto all other observations
bys global_start: replace global_start = global_start[1]
by global_start : replace global_end = global_end[1]
//evaluate for all other observations whether their event date range
overlaps with current "global" event date range
replace in_range = ((start_date >= global_start & start_date <=
global_end) | (end_date >= global_start & end_dat<=global_end)) &
event!="`el'"
//sum it up and save to temporary variable
egen `tmp_oo' = sum(in_range)
//copy the sum from the temp variable to the variable other_obs ONLY
for the current event (as in local macro -el-)
replace other_obs = `tmp_oo' if event=="`el'"
//drop temp variable
drop `tmp_oo'
}
} //ending quiet mode
//drop some variables no longer needed
drop global_start global_end in_range
/* END EXAMPLE */
On 4/19/07, Jarl Svartsj� <[email protected]> wrote:
Dear Statalist,
I have two date variables in my dataset, which define
the start and end dates for a certain event. For each
observation in the dataset, I'd like to count the
number of other observations in the dataset that
overlap with this event window.
I.e.
Event Start date End date Simultaneous events
-----------------------------------------------------------------------------------
XYZ 11jan04 07feb04 ???
ZZZ 11jan04 08feb04 ???
YYY 14jan04 22jan04 ???
XXX 21jan04 13mar04 ???
ZZY 30jan04 04feb04 ???
aso.aso.
Which command should I use?
Thanks!
-JS
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