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Re: How to plot linear regression relation of two array? [message #65032]

Mon, 09 February 2009 15:09

Vince Hradil
Messages: 574
Registered: December 1999

Senior Member

On Feb 9, 3:21 pm, Hu <jha...@gmail.com> wrote:
> On Feb 9, 1:13 pm, Vince Hradil <vincehra...@gmail.com> wrote:
>
>
>
>> On Feb 9, 2:51 pm, Hu <jha...@gmail.com> wrote:
>
>>> On Feb 9, 12:12 pm, Vince Hradil <vincehra...@gmail.com> wrote:
>
>>>> On Feb 9, 1:45 pm, Hu <jha...@gmail.com> wrote:
>
>>>> > Hi,
>
>>>> > I am trying to plot a linear regression relation of two array
>>>> > (supposing A and B) by using IDL. What I want is to got a chart like
>>>> > this link shows (the group is unable to post figure directly):http://serc.carleton.edu/images/introgeo/teachingw data/LeastSquaresGr...
>
>>>> > especially, How can I got the black straight line and the coefficients
>>>> > R^2 ?
>
>>>> > Thanks
>
>>>> Have you looked in the help for linfit()?
>
>>> BTW, I set MEASURE_ERRORS to SQRT(ABS(Y)), just follow the example,
>>> but what is MEASURE_ERRORS? and what is R^2 mean in the above picture?
>
>>> Thank you very much
>
>> Sounds like you're using REGRESS() not LINFIT()?
>
>> I'd use LINFIT() to get the nice line
>> and use CORRELATE() to get the Pearson correlation coefficient. I
>> think CORRELATE() gives you the Pearson correlation coefficient, r,
>> which, in this case can be squared to get R^2.
>
> I use Linfit(), this function need a MEASURE_ERRORS parameter to run.
> Anyway, I will try your suggestion, CORRELATE()
>
> Tnaks

Oh right, I've just never used it. Maybe these will help?
http://en.wikipedia.org/wiki/Linear_regression
http://en.wikipedia.org/wiki/Coefficient_of_determination

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[Message index]

		Re: How to plot linear regression relation of two array? By: Vince Hradil on Mon, 09 February 2009 15:09
		Re: How to plot linear regression relation of two array? By: pgrigis on Mon, 09 February 2009 14:39
		Re: How to plot linear regression relation of two array? By: Hu on Mon, 09 February 2009 13:21
		Re: How to plot linear regression relation of two array? By: David Fanning on Mon, 09 February 2009 13:20
		Re: How to plot linear regression relation of two array? By: Vince Hradil on Mon, 09 February 2009 13:13
		Re: How to plot linear regression relation of two array? By: Hu on Mon, 09 February 2009 12:51
		Re: How to plot linear regression relation of two array? By: Hu on Mon, 09 February 2009 12:42
		Re: How to plot linear regression relation of two array? By: Vince Hradil on Mon, 09 February 2009 12:12

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