topic Re: How to create date variable in SAS Data Management

How to create date variable

venkatnaveen — Wed, 25 Mar 2015 17:27:04 GMT

I got cmstdtc values like

2003

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

Re: How to create date variable

naveen_srini — Wed, 25 Mar 2015 17:33:29 GMT

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.

Re: How to create date variable

venkatnaveen — Wed, 25 Mar 2015 17:47:26 GMT

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

Re: How to create date variable

Reeza — Wed, 25 Mar 2015 18:09:25 GMT

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?

Re: How to create date variable

venkatnaveen — Fri, 27 Mar 2015 10:45:32 GMT

For anyday within a month

Re: How to create date variable

LinusH — Tue, 31 Mar 2015 07:36:22 GMT

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.

Re: How to create date variable

Jim_G — Tue, 31 Mar 2015 12:50:40 GMT

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;

Re: How to create date variable

data_null__ — Tue, 31 Mar 2015 13:02:25 GMT

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.