From: Richard Williams <[email protected]>
Reply-To: [email protected]
To: [email protected]
Subject: Re: st: Interpolation using cipolate
Date: Wed, 14 Apr 2004 07:14:49 -0500
At 11:41 AM 4/14/2004 +0000, you wrote:
Sorry for double posting
Dear all,
A naive question. I just insalled cipolate to fill missing values for one
variable. The documentation tells me that interpolation is done using two
points before and two points after the missing value. That said, why is it
that the procedure requires a second variable? In other words, for
replacing missing values in variable y, why we need to include variable x
in the command?
. cipolate y x, gen(yprime).
I don't know about -cipolate-, but the docs for -ipolate- (reference manual
G-M, pp. 182-183) say that Y is a function of X. The value for
interpolated Y is computed using values from the surrounding Xs and Ys that
are not missing.
If you are going to interpolate, your data have to be sorted in some way,
right? So having an X accomplishes that. The distance between Xs will be
related to the interpolated differences between Ys.
-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
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