Date: Mon, 24 Nov 2003 18:59:55 +0000
Reply-To: John Whittington <John.W@MEDISCIENCE.CO.UK>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: John Whittington <John.W@MEDISCIENCE.CO.UK>
Subject: Re: how to use lag
In-Reply-To: <5.0.2.1.2.20031124115743.02867110@mail.wispertel.net>
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At 12:08 24/11/03 -0700, Richard Read Allen wrote:
>John, Venky and Helen,
>I realized that my solution would not cross id boundaries when I submitted it
I presume you mean that it WOULD 'cross id boundaries' (which is undesired
functionality for Helen).
>.... but was mostly just trying to inform Helen not to use the lag in a
>conditional statement unless absolutely necessary and show her one
>possible solution that did work for her problem as it was stated. I left
>it to her to fill in the details. I should not have done that. My apologies.
Richard, having misread your code and made a false accusation about it, I'm
hardly in a position to be critical or to expect anyone else to apologise -
and, in any event, you approach was actually better than mine. Because I
was thinking in generalisations, I unnecessarily introduced the temporary'
variable lag_y, whereas, as you've illustrated, in Helen's case it is
sufficient to RETAIN variable x itself.
Kind Regards
John
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