Rate in Person years

[learn2]

If I have a dataset structure like this, how can I code to determine the rate = visits/person years?

ID	Total number of Visits	Start Date	End date
1	15	Jan21,2002	April4,2008
2	4	Feb6,1991	June8,2015
3	7	June9,1999	July5,2000

[Reeza]

How are you accounting for partial years? If they're in a year at any point are they included?

[learn2]

What do people usually do for partial years, pretty new to this and kind of unsure of how to go about this 

[ballardw]

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@learn2 wrote:

What do people usually do for partial years, pretty new to this and kind of unsure of how to go about this 

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Person years can change between usage groups possibly even within an organization on a per topic basis.

One possible way would be to use the YRDIF function with the two dates in question with the "ACT/ACT" basis as that returns years with a decimal portion.

data example;
   years= yrdif('21MAR1987'd,'17Jul2001'd,'ACT/ACT');
run;

for example returns approximately 14.323 years.

[learn2]

Thanks!

[SuryaKiran]

Hello,

This might help:

data have;
input ID Visits Start :$15. End :$15.;
datalines;
1 15 Jan21,2002 April4,2008
;
run;

data want;
set have;
start_date=input(cats(compress(scan(start,1,','),,'a'),substr(start,1,3),scan(start,2,',')),date9.);
end_date=input(cats(compress(scan(end,1,','),,'a'),substr(end,1,3),scan(end,2,',')),date9.);
years=int((end_date-start_date)/365.24);
run;

Please provide your sample data in the form of datastep.