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st: RE: RE: carryforward
From
Nick Cox <[email protected]>
To
"'[email protected]'" <[email protected]>
Subject
st: RE: RE: carryforward
Date
Mon, 23 Jan 2012 17:58:47 +0000
If this method is one of imputing missing values that in practice will be varying by a constant that was the last observed value, then as Tony implies it clearly can be problematic.
But the method of replacing missing values by previous non-missing values is one I often use with small datasets entered by hand. When the observations come in blocks, I only need to type in values for the first identifier in each block, and then -replace- appropriately.
Sometimes datasets arrive like that too. Only the first value in a block of some blocked variable is explicit, so you have to fill in (or fill out) implied similar values.
Nick
[email protected]
Lachenbruch, Peter
This method has been seriously questioned and gives very poor answers generally. A true p-value may be reported anywhere from 0.01 to0.15 when it should be 0.05. I strongly urge it not be used.
________________________________________
From: [email protected] [[email protected]] On Behalf Of David Kantor [[email protected]]
Once again, thanks to Kit Baum, a new version of -carryforward- is
available on SSC.
This upgrade adds the -if- and -in- qualifiers.
Actually, the upgrade was written a long time ago, but never got
uploaded until now. Sorry, if that was my fault.
-carryforward- carries values from one observation to the next,
filling in missing values.
-ssc install carryforward-
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