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Re: st: RE: AW: ratio function

From   Steve Samuels <>
Subject   Re: st: RE: AW: ratio function
Date   Thu, 1 Apr 2010 09:30:10 -0400

2010/4/1 Roman Kasal <>:
> but it ignores unpaired data :(

And it should.   Data (x,y) (1,2) (2,4) (3,6) (100,.)    will give an
entirely different view of the data if the unpaired observation is
included in a mean or ratio calculation.  Or consider data with x
missing in half the pairs and y missing in the other half; the ratio
of means would be meaningless.

The formulas for standard errors for ratios  assume that the data are
paired. Formally, they are based on the residual MSE of a regression
of y on x through the origin. You cannot do that regression with
unpaired data.

If your concern is missing data, the solution is to impute the missing
values before analysis.

Steven Samuels
18 Cantine's Island
Saugerties NY 12477
Voice: 845-246-0774
Fax:    206-202-4783
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