Fillng in Missing Values based on previous observations

[llt34c]

I need to replace missing values in my data set. I need SAS to reference the previous observation and calculate the date of the current observation based on the previous observation.

data Example; set Example1;
If Date = "." then do;
Date = Obs - 1 ....... Date+1;
Run;

Thanks.

[rivieralad]

Hi

There is a LAG function in SAS that allows you to reference the value of a variable on the previous observation.

It is well documented and works along the lines of

If date = . then date = lag(date) + 1;

Cheers

Chris

[PGStats]

Use a retained variable:

data want;
retain previousDate;
set have;
date = coalesce(date, intnx("DAY", previousDate, 1));
previousDate = date;
drop previousDate;
run;