How to create date variable

[venkatnaveen]

I got cmstdtc values like

            2003

            2009

            2009

           Aug 2013

          Aug-12-2014

i need to substract or add this dates with another dates which are full length dates

Aug-12-2014

June-12-2014

Apr-12-2014

[naveen_srini]

Well well, Have i not understood your question clearly or could you explain better please. Are you trying to extract date from the top 5 obs in your sample and then add or minus with other dates?It's difficult to understand what you are trying to achieve. Please provide your sample(have) dataset and (want) dataset.

[venkatnaveen]

I have

2003

2007

2008

AUG-2009

AUG-2003

SEP-12-2009 and

iwant

i want results like which day the patient came to the visit

7

10

15

16

10

[Reeza]

So if you have 2003 what date do you want to map that to?

Same for 2007/2008?

And if you have month & year what are you assuming the day is? Can you assume the first, last or should you assume middle of the month?

[venkatnaveen]

For anyday within a month

[LinusH]

You are still way to vague.

Show exactly what kind of output you desire based on input data, and try to explain in more words why/how.

[Jim_G]

If first day of the month is OK, try this code.    Jim

data;

input  dat  $20.;

len=length(dat);     monyr='          ';

if len=4 then do;

  ndat=input(dat,4.); 

  date=mdy(1,1,ndat);

end;

if len=8 then date=input(dat,monyy10.);

if len gt 8 then do;

   mon=scan(dat,1);  day=scan(dat,2);  yr=scan(dat,3);

   *monyr=mon||yr;

   substr(monyr,1,3)=mon;  substr(monyr,4,4)=yr;

   date=input(monyr,monyy10.);

   nday=input(day,2.);  date=date+nday-1;

end;

format date  mmddyy10.;

cards;

2003

2007

2008

AUG-2009

AUG-2003

SEP-12-2009

proc print;    run;

[data_null__]

In clinical trials data processing there is "always" a document that provides information on how incomplete dates (or anything else) should be imputed.  You should read that.

Perhaps something like this.

01-JUL-year when you have only the year.

15-mon-year when you have only month and year.

Sometimes the imputation is slightly different if the date is a start versus an end date.

The point is, the answer to the imputation is in the documentation for the analysis and you already have that.