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Re: comparison between two value in a sample, please help...
Posted:
Aug 17, 2012 9:39 PM


On Fri, 17 Aug 2012 01:49:39 0400, Rich Ulrich <rich.ulrich@comcast.net> wrote:
[snip, a bunch] > >I *think* what follows is a safe, conservative procedure  >The minimum, proper fitted equation will show no less error >than the measurement error. For that, the pooled SD is
Keep in mind that the MSresidual is an estimate of the variance (which is the square of the standard deviation) of the residual.
When I was learning to use regression, it helped me when I realized that fact. Then I started making a point of noticing that variance, and taking the square root ... just to make sure that I was still analyzing the same set that I thought I was, and that nothing was going strange.
>about 42, or the "Meansquareresidual" is the square of >42, with 10 d.f. Take the Mean square for Regression from >the 5point regression and divide it by *this* residual, >instead of the computed residual, to get the safe Ftest.
Oops! slligh correction  For the 5 point regression, each point is the average of three measures. The SD of the *3* taken separately is 42; the SD of the average is, naturally, the raw SD divided by the square root of N, or sqrt(3). Or  the MS is not 42squared, but is 42squared, divided by 3.
> >The ratio of the two socalled Residual terms can be used as >a test of whether the regression is "over fitted". > Still useful, but you do use the corrected value.
 Rich Ulrich



