... by the way: a RETAIN statement normally makes no sense for a dataset variable. How does it work? RETAIN prevents a variable to be set to missing at the end of the internal loop. After that, all variables are loaded with the values of the next obs. So you can prevent a variable from being initialized, anyway it gets a new value from the new obs. So define a new variable, not a existing one. This new variable you can use to save a value.

data ...; retain xx_dummy; set ...; if lag_xx ne . then do; xx_dummy=lag_xx; end; else do; lag_xx=xx_dummy; /* or whatever should be in there */ end; ... run;

With that you fill up lag_xx with the previous value if it's missing. However it is not clear to me, what you REALLY want to do. Is lag_xx really needed? Or do you want to treat with XX and do something like the above, maybe not only replace the missing, also add 30? Gerhard

On Thu, 5 Apr 2007 02:03:20 -0400, Yosef Sugiharto Adikusumo <YSAdikusumo@BANKBII.COM> wrote:

>Hi,I have a dataset with the following values. > >id date_1 date_2 XX lag_XX >1AA 08aug06 23aug06 54 . >1AA 08sep06 . . 54 >1AA 08oct06 . . . >1AA 08nov06 . . . >2BB 18aug06 3sep06 20 . >2BB 18sep06 . . 20 >2BB 18oct06 . . . >3CC 05aug06 18aug06 10 . >3CC 05sep06 . . 10 > >How can I change it to the following specification. >such that the output looks like this > >id date_1 date_2 XX lag_XX >1AA 08aug06 23aug06 54 . >1AA 08sep06 . 84 54 >1AA 08oct06 . 124 84 >1AA 08nov06 . 154 124 >2BB 18aug06 3sep06 20 . >2BB 18sep06 . 50 20 >2BB 18oct06 . 80 50 >3CC 05aug06 18aug06 10 . >3CC 05sep06 . 40 10 > >think I have to use a retain statement for lag_XX and update to XX >variable??? but I dont know how to proceed. > >Thanks you all for your help as always >YS