Thank you Nick. The dataset I am working with, however,
contains non-disjoint records, can the approach you provided be
modified to address overlapping service dates? When records do
overlap, I do not want to double-count.
--Clint Thompson
On 11 May 2004 at 20:23, Nick Cox wrote:
> In program 2 you have several problems.
>
> The local macro 0 contains what you type
> after the program name, in your case
> a (probably unexpanded) varlist. Although
> the -syntax- statement will expand it,
> that doesn't affect `0'. So the first step is
> to go to
>
> program var_rep
> version 8
> syntax varlist(numeric)
> local n 10
> foreach var of local varlist {
> forvalues i = 14610(1)`n' {
> replace `var' = 1 if (`i' >= svcdate & `i' <= svcdate_end),
> by(enrolid)
> }
> }
> end
>
> But that still leaves two bugs that I can see:
>
> 1. 14610(1)10 won't go anywhere. You mean 14610/14619.
>
> 2. -replace- doesn't take a -by()- option.
>
> However, given your problem, a direct attack
> is possible, I believe, without any loops whatsover or
> indeed any programs whatsoever.
>
> Your structure appears to be
>
> enrolid svcdate svcdate_end
>
> First check that the dates are
> the right way round in every case
>
> . assert svcdate <= svcdate_end
>
> Possibly you even have several
> records for each person. That's no
> problem, so long as they are disjoint.
>
> For each person, you want #days in
> service between 1 Jan 2000 and
> 31 Dec 2001. The length of relevant service is
>
> min(svcdate_end, mdy(12,31,2001))
> -max(mdy(1,1,2000),svcdate)
>
> So I think what you want is
>
> gen cont = 1 + min(svcdate_end, mdy(12,31,2001)) -
> max(mdy(1,1,2000),svcdate) egen sumservice = sum(cont), by(enrolid)
>
> Note the 1, based on the assumption that anyone who
> arrived and left the same day is regarded as serving
> 1 day, etc. Delete according to taste.
>
> Nick
> [email protected]
>
> [email protected]
>
> > I have two small (and clumsy) programs wherein the objective is
> > to create a variable for each day over a two year time frame
> > (01Jan2000 - 31Dec2001) then assign the value 1 if the subject
> > was on service, as defined by two variables: svcdate &
> > svcdate_end. My programs are pasted below; the first one
> > (var_gen) generates the variables as expected (note that I
> > limited variable generation to just the first 10 days in 2000). The
> > second program, however, executes when run but it does not return a 1
> > where it should. I suspect that the problem may be with the forvalues
> > loop in the foreach statement. Any advice or suggestions? My
> > ultimate objective is to sum the total number of days each subject was
> > on service over the two year period. Thank you. Clint Thompson
> >
> > Program #1:
> > program var_gen
> > version 8
> > local N 10
> > forvalues i = 1(1)`N' {
> > gen day`i' = 0
> > }
> > end
> >
> >
> > Program #2:
> > program var_rep
> > version 8
> > syntax varlist(numeric)
> > local n 10
> > foreach var of local 0 {
> > forvalues i = 14610(1)`n' {
> > replace `var' = 1 if (`i' >= svcdate & `i' <=
> > svcdate_end), by(enrolid)
> > }
> > }
> > end
>
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