## Events within 6 months of a date

Frequent Contributor
Posts: 138

# Events within 6 months of a date

Hi all,

I have data at the person-event level--that is, each row represents one event for one person. The data include ID number, a fixed date at the person level (ie, each time an ID recurs, this date will be the same), an event type variable, and an event date variable. IDs can recur.

ID          Fixed date          Event type          Event date

1             5/4/2013               A                    10/12/2012

1             5/4/2013               B                     6/7/2013

1             5/4/2013               A                     1/1/2013

2             9/2/2012               B                     10/4/2012

2             9/2/2012               B                     11/1/2012

3            10/4/2014              A                      3/4/2013

What I want to be able to evaluate is whether a specific type of event occurred within 6 months of the fixed date (that is, whether the event date is within 6 months of the fixed date).

Any help is much appreciated.

Super Contributor
Posts: 578

## Re: Events within 6 months of a date

I think its as simple as using intck function.

Super User
Posts: 9,599

## Re: Events within 6 months of a date

Intnx would be easier no?

data have;

id=1; fixed_date='05APR2013'd; event_type="A"; Event_date='10DEC2012'd; output;

id=1; fixed_date='05APR2013'd; event_type="A"; Event_date='06JUL2013'd; output;

run;

data want;

set have;

if fixed_date <= event_date <= intnx('month',fixed_date,6) then flag="Y";

run;

Super Contributor
Posts: 578

## Re: Events within 6 months of a date

Six of one...half a dozen of the other.

Frequent Contributor
Posts: 138

## Re: Events within 6 months of a date

Hi,

I tried this solution (intnx), and it seemed to work. While QCing, I checked a sample date (August 23, 2013) and tested to see what the program would return as the date 6 months after. It returned February 1st, 2014, which is 162 days later. Considering this, I'm confused about how it's calculating the time period of 6 months.

Super User
Posts: 9,599

## Re: Events within 6 months of a date

There are other options in the intnx function: http://support.sas.com/documentation/cdl/en/lrdict/64316/HTML/default/viewer.htm#a000212700.htm

May need to put  intnx('month',fixed_date,6,'same')

Posts: 4,738

## Re: Events within 6 months of a date

6 months: Is this by calendar date or number of days (=180)?

If it's calendar date then code as below should do.

data sample;

input ID:\$5. Fixed_date:mmddyy10. Event_type:\$5. Event_date:mmddyy10.;

format Fixed_date Event_date date9.;

within6month_flg=0;

select;

when (Fixed_date<=Event_date)

do;

if Fixed_date>intnx('month',Event_date,-6,'s') then within6month_flg=1;

end;

when (Fixed_date>Event_date)

do;

if Fixed_date<intnx('month',Event_date,6,'s') then within6month_flg=1;

end;

end;

datalines;

1 5/4/2013 A 10/12/2012

1 5/4/2013 B 6/7/2013

1 5/4/2013 A 1/1/2013

2 9/2/2012 B 10/4/2012

2 9/2/2012 B 11/1/2012

3 10/4/2014 A 3/4/2013

;

run;

PROC Star
Posts: 8,167

## Re: Events within 6 months of a date

No confusion necessary! Intck is simply checking # of boundaries crossed.

There are more than 180*2 days in a year. Using months and same is simply counting (given, say, startdate is 05jan2014 and end date is 04mar2014) how many month boundaries are crossed between the two (with the day indicating the boundary is the 5th of the month.

Posts: 1,147

## Re: Events within 6 months of a date

data  have(where=(0 <= dur2 <= -6));

input ID\$          Fixed_date :mmddyy10.           Event_type \$         Event_date :mmddyy10. ;

dur2= intck('month',Fixed_date,Event_date) ;

format Fixed_date Event_date date9. ;

cards;

1             5/4/2013               A                    10/12/2012

1             5/4/2013               B                     6/7/2013

1             5/4/2013               A                     1/1/2013

2             9/2/2012               B                     10/4/2012

2             9/2/2012               B                     11/1/2012

3            10/4/2014              A                      3/4/2013

;

run;

Thanks,

Jag

Thanks,
Jag
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