I have a list of prisoners and when their prison term started (PrisonStart) and when it ended (PrisonEnd). If they're still in prison, PrisonEnd is blank.
I would like to flag prisoners who were in prison at least one full calendar month during a 6-month period (1/1/16 to 5/30/16).
compute PeriodBeg = date.mdy(01,01,16).
compute PeriodEnd = date.mdy(05,30,16).
formats PeriodBeg PeriodEnd (adate10).
execute.
Any suggestions for how best to go about this? Seems I might need to compare prisoners' start and end dates separately for each month during the 6-month period (like below), and then select any prisoner with at least one full month, but I'm wondering if there's a more efficient way.
if ((PrisonStart le [January 1, 2016]) and (PrisonEnd ge ([January 31, 2016]) | missing(PrisonEnd))) InPrisonJan = 1.
if ((PrisonStart le [February 1, 2016]) and (PrisonEnd ge ([February 28, 2016]) | missing(PrisonEnd))) InPrisonFeb = 1.
etc.
execute.
Some sample data below. The first two prisoners should be flagged as having been in prison for at least one full calendar month during the 6-month period (OneMonth = 1). The last three prisoners were not in prison for at lease one full calendar month during the 6-month period (OneMonth = 0).
data list list /PrisonerID (F8.0) PrisonStart (adate10) PrisonEnd (adate10) PeriodBeg (adate10) PeriodEnd (adate10).
begin data
1 10.3.14 7.12.16 1.1.16 5.30.16
2 2.9.16 4.1.16 1.1.16 5.30.16
3 5.2.16 10.11.16 1.1.16 5.30.16
4 12.1.13 2.8.14 1.1.16 5.30.16
5 1.7.16 1.20.16 1.1.16 5.30.16
6 1.1.17 3.2.17 1.1.16 5.30.16
end data.
The following syntax avoids mentioning the last day of each month separately, so it could be used to automate across any number of months. The trick to check if the date is the last day of the month, is by checking day "0" of NEXT month:
do repeat inpr=inPrison1 to inPrison5/ mon=1 to 5.
compute inpr=( PrisonStart<=date.dmy(1,mon,2016) and
(PrisonEnd>=date.dmy(0,mon+1,2016) or missing (PrisonEnd)) ).
end repeat.