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Re: st: RE: carrying observations forward if criteria met


From   David Kantor <kantor.d@att.net>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: carrying observations forward if criteria met
Date   Fri, 03 Feb 2012 10:23:43 -0500

At 04:00 PM 2/2/2012, Nick Cox wrote:
David Kantor keeps an eye on the list and can speak for his -carryforward- (SSC).
..in response to the comment from Laura Hendrix:
This is similar to the "carryforward" ado file but I believe that only
replaces missing values?

Indeed, -carryforward- fills in missing values -- never replaces non-missing.
It also works on long-shaped data, so there are two reasons for it to be inapplicable.

I might add that, if your data were long-shaped, then you could do a cascading replace operation. However, carryforward would still not apply; you would need to write your own code to do it.

In any case, I agree with Nick that it would be wise to keep a copy of the original values.

[...]
However, I am queasy about supporting your changing your data, which someone might regret, so advise that you do this on a clone of your data, or equivalently keep a copy of the original variables somewhere.
[...]

HTH
--David

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