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LINFIT CHISQ and SIGMA values are correct?? [message #91593]

Tue, 04 August 2015 12:54

Krishnakumar M.A
Messages: 19
Registered: March 2013

Junior Member

Hi,

I was trying to do a linfit in the following data (I'm using IDL 6.3).

---------------------------------------------------

x = [150.0, 235.0, 325.0, 410.0, 610.0]
y = [200.0, 35.0, 8.4, 3.0, 0.6]
err = [25.0, 5.0, 2.1, 0.8, 0.2]

result = linfit(alog10(x),alog10(y),MEASURE_ERRORS=alog10(err), CHISQ=chi, COVAR=covmatrix, SIGMA=error, YFIT=fit)

---------------------------------------------------

It gave me surprisingly odd values for CHISQ and SIGMA. The values are given below.

---------------------------------------------------

result
11.6899 -4.29070
chisq
0.00799291
sigma
4.32894 1.66352

---------------------------------------------------

Fit result looked good, but the values of sigma and chisq are way off. I believe that the chisq it gives is reduced chisq. Is there anything went wrong in the fitting procedure, or are there any issues with the linfit algorithm?

Please let me know whether I'm doing it right or not.

Thanks,
Krishnakumar

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[Message index]

		LINFIT CHISQ and SIGMA values are correct?? By: Krishnakumar M.A on Tue, 04 August 2015 12:54
		Re: LINFIT CHISQ and SIGMA values are correct?? By: wlandsman on Tue, 04 August 2015 19:19
		Re: LINFIT CHISQ and SIGMA values are correct?? By: Krishnakumar M.A on Wed, 05 August 2015 00:07
		Re: LINFIT CHISQ and SIGMA values are correct?? By: Helder Marchetto on Wed, 05 August 2015 00:23

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