Hi Edward. I also think it is some math some where.
I have a feeling, that it is the creating of Monte Carlo data with 2 sigma? and then some log/exp calculation of R2eff. If the errors are 2 x times over estimated, the chi2 values are 4 as small, and the space should be the same? best Troels 2014-08-29 17:06 GMT+02:00 Edward d'Auvergne <[email protected]>: > I've just added the 2D Grace plots for this to the repository (r25444, > http://article.gmane.org/gmane.science.nmr.relax.scm/23194). They are > also attached to the task for easier access > (https://gna.org/task/index.php?7822#comment107). From these plots I > see that the I0 error appears to be reasonable, but that the R2eff > errors are overestimated by 1.9555. > > The plots are very, very different. It is clear that > chi2_jacobian=True just gives rubbish. It is also clear that there is > a perfect correlation in R2eff when chi2_jacobian=False. The plot > shows absolutely no scattering, therefore this indicates a crystal > clear mathematical error somewhere. I wonder where that could be. It > may not be a factor of 2, as the correlation is 1.9555. So it might > be a bug that is more complicated. In any case, overestimating the > errors by ~2 and performing a dispersion analysis is not possible. > This will significantly change the curvature of the optimisation space > and will also have a huge effect on statistical comparisons between > models. > > Regards, > > Edward > > > > On 29 August 2014 16:56, Troels Emtekær Linnet <[email protected]> wrote: >> The default is now chi2_jacobian=False. >> >> You will hopefully see, that the errors are double. >> >> Best >> Troels >> >> 2014-08-29 16:43 GMT+02:00 Edward d'Auvergne <[email protected]>: >>> Terrible ;) For R2eff, the correlation is 2.748 and the points are >>> spread out all over the place. For I0, the correlation is 3.5 and the >>> points are also spread out everywhere. Maybe I should try with the >>> change from: >>> >>> relax_disp.r2eff_err_estimate(chi2_jacobian=True) >>> >>> to: >>> >>> relax_disp.r2eff_err_estimate(chi2_jacobian=False) >>> >>> How should this be used? >>> >>> Cheers, >>> >>> Edward >>> >>> >>> >>> On 29 August 2014 16:33, Troels Emtekær Linnet <[email protected]> >>> wrote: >>>> Do you mean terrible or double? >>>> >>>> Best >>>> Troels >>>> >>>> 2014-08-29 16:15 GMT+02:00 Edward d'Auvergne <[email protected]>: >>>>> Hi Troels, >>>>> >>>>> I really cannot follow and judge how the techniques compare. I must >>>>> be getting old. So to remedy this, I have created the >>>>> test_suite/shared_data/dispersion/Kjaergaard_et_al_2013/exp_error_analysis/ >>>>> directory (r25437, >>>>> http://article.gmane.org/gmane.science.nmr.relax.scm/23187). This >>>>> contains 3 scripts for comparing R2eff and I0 parameters for the 2 >>>>> parameter exponential curve-fitting: >>>>> >>>>> 1) A simple script to perform Monte Carlo simulation error analysis. >>>>> This is run with 10,000 simulations to act as the gold standard. >>>>> >>>>> 2) A simple script to perform covariance matrix error analysis. >>>>> >>>>> 3) A simple script to generate 2D Grace plots to visualise the >>>>> differences. Now I can see how good the covariance matrix technique >>>>> is :) >>>>> >>>>> Could you please check and see if I have used the >>>>> relax_disp.r2eff_err_estimate user function correctly? The Grace >>>>> plots show that the error estimates are currently terrible. >>>>> >>>>> Cheers, >>>>> >>>>> Edward >>>>> >>>>> _______________________________________________ >>>>> relax (http://www.nmr-relax.com) >>>>> >>>>> This is the relax-devel mailing list >>>>> [email protected] >>>>> >>>>> To unsubscribe from this list, get a password >>>>> reminder, or change your subscription options, >>>>> visit the list information page at >>>>> https://mail.gna.org/listinfo/relax-devel _______________________________________________ relax (http://www.nmr-relax.com) This is the relax-devel mailing list [email protected] To unsubscribe from this list, get a password reminder, or change your subscription options, visit the list information page at https://mail.gna.org/listinfo/relax-devel
