Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » sci.math.* » sci.stat.math.independent

Topic: comparison between two value in a sample, please help...
Replies: 3   Last Post: Nov 18, 2012 10:02 AM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Richard Ulrich

Posts: 2,848
Registered: 12/13/04
Re: comparison between two value in a sample, please help...
Posted: Aug 17, 2012 9:39 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

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 MS-residual 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 "Mean-square-residual" is the square of
>42, with 10 d.f. Take the Mean square for Regression from
>the 5-point regression and divide it by *this* residual,
>instead of the computed residual, to get the safe F-test.


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 42-squared, but is 42-squared, divided
by 3.

>
>The ratio of the two so-called 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



Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.