Date:         Thu, 25 Aug 2011 14:19:34 -0700
Reply-To:     "Nordlund, Dan (DSHS/RDA)" <NordlDJ@DSHS.WA.GOV>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Nordlund, Dan (DSHS/RDA)" <NordlDJ@DSHS.WA.GOV>
Subject:      Re: Lag values
In-Reply-To:  <941871A13165C2418EC144ACB212BDB00205D838@dshsmxoly1504g.dshs.wa.lcl>
Content-Type: text/plain; charset=utf-8

Unfortunately, I had a cut ana paste accident here. :-)  Just ignore the beginning, and go straight the end of the post

> -----Original Message-----
> From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of
> Nordlund, Dan (DSHS/RDA)
> Sent: Thursday, August 25, 2011 2:04 PM
> To: SAS-L@LISTSERV.UGA.EDU
> Subject: Re: Lag values
>
<<<snip>>>
>
> > -----Original Message-----
> > From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of
> > sas8832@HOTMAIL.CO.UK
> > Sent: Thursday, August 25, 2011 1:30 PM
> > To: SAS-L@LISTSERV.UGA.EDU
> > Subject: Re: Lag values
> >
> > panel dataset
> >
> > id year quarter variablex lag_variablex
> > 1   2000 1         10            .
> > 1   2000 2          5            10
> > 1   2000 3          .             5
> > 1   2000 4          20             .
> >
> > When variablex is missing for the previous quarter, i want
> > lag_variablex=.
> > rather than equal to the previous available value for variable x. I
> > have
> > already filled holes (ie missing quarters).
> >
> > Thanks
>
> Here is one possibility:
>
> data have;
>   input id year quarter variablex ;
> cards;
> 1   2000 1         10
> 1   2000 2          5
> 1   2000 3          .
> 1   2000 4          20
> 2   2000 1         10
> 2   2000 2          5
> 2   2000 3          .
> 2   2000 4          20
> ;
> run;
>
> data want;
>   set have ;
>   by id;
>   lag_variablex = lag(variablex);
>   if first.id then lag_variablex = .;
> run;
>
> proc print;
> run;
>
> I added some data for another id and set the lagged value to missing
> when first.id = 1.  If you don't want that, just delete the if
> statement.
>
>
> Hope this is helpful,
>
> Dan
>
> Daniel J. Nordlund
> Washington State Department of Social and Health Services
> Planning, Performance, and Accountability
> Research and Data Analysis Division
> Olympia, WA 98504-5204