Bryan Shaw
Cameco Corp
I may be simplest just to export and use a freeware or shareware
regression tool. I love gnuplot which is a good bear-bones xy grapher and
has equation fitting built in ( FIT command ).
Jeff Gamey
<[EMAIL PROTECTED]> To: [EMAIL PROTECTED]
Sent by: cc:
[EMAIL PROTECTED] Subject: Re: [geonet]: linear
regression
eosoft.com
11/14/00 12:40 PM
Please respond to
geonet
Bill-
Thanks for the outline, but my application is rather more rudimentary than
you give me credit for. I've got a simple spread of points that
approximate a straight line. I can use the linear regression function in
Geosoft to calculate slope and intercept, but I really want to know how
well the points fit that line and I can't find a Geosoft function to do it.
-Jeff
At 02:22 PM 11/14/00 , you wrote:
>Jeff:
>
>The methodology we have been using is to use the technique of
bootstrapping,
>or resampling.
>
>Take your original line data, randomaly select a subset of all teh data
>points.
>Recalculate the slope.
>Repeat random resampling of the full data set
>Recalculate slope.
>
>Repeat process a number of times...
>
>You can then calculate the mean slope and derive an estimate of the error
>(standard deviation of that slope).
>This procedure gives you a depth estimate and a error on your depth
>estimate.
>
>Of course what it really serves to do is to emphasise that you really
don't
>know very much about the depth of the longer wavelength portion of your
>spectrum since you only have a very small number of points in this portion
>of your curve.
>
>Bill Morris
>
>PS Kristi Markham one of my grad students gave talk on this subject at
last
>years EGS conference, and is actively writing a paper on this subject.
>
>
>
>
>----- Original Message -----
>From: "Jeff Gamey" <[EMAIL PROTECTED]>
>To: <[EMAIL PROTECTED]>
>Sent: Tuesday, November 14, 2000 7:42 AM
>Subject: [geonet]: linear regression
>
>
> > I can run linear regression to get the slope and intercept of my data,
but
> > I'd like a measure of error of fit to that line. Does anyone have a
way
>to
> > do that apart from (a) manually inputting the slope and intercept into
a
> > math expression for error of fit, then (b) calculating the std dev of
the
> > error?
> >
> > Having it included in the linear regression GX would be ideal. If
someone
> > wants to talk me through it, I'll try to modify it myself.
> >
> > *******************
> > * Jeff Gamey (4tj)
> > * Environmental Sciences Division [EMAIL PROTECTED]
> > * Oak Ridge National Laboratory (865) 574-6316 tel
> > * POBox 2008, Bldg 1505, MS6038 (865) 576-8646 fax
> > * Bethel Valley Rd., Oak Ridge, TN (865) 599-0820 cell
> > * 37831-6038
> >
> > _______________________________________________________
> > More mailing list info
http://www.geosoft.com/support/listserv/index.html
> >
>
>_______________________________________________________
>More mailing list info http://www.geosoft.com/support/listserv/index.html
*******************
* Jeff Gamey (4tj)
* Environmental Sciences Division [EMAIL PROTECTED]
* Oak Ridge National Laboratory (865) 574-6316 tel
* POBox 2008, Bldg 1505, MS6038 (865) 576-8646 fax
* Bethel Valley Rd., Oak Ridge, TN (865) 599-0820 cell
* 37831-6038
_______________________________________________________
More mailing list info http://www.geosoft.com/support/listserv/index.html
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