On Wed, Oct 15, 2008 at 7:30 PM, Tyler Reddy <TREDDY@xxxxxx> wrote:
Okay, so I'll basically just need to get the rms noise (NOT S/N) for my T1 and T2 spectra at various fields. I've been using S/N values for the NOE calculations so that explains why those errors seemed so large. I'd like to find a reference for the rms equation which seems to be:
Those would be quite big errors :)
[sqrt(2)]*(baseline noise height)/4
I think: sigma_h = rmsd(noise), is sufficient, where sigma_h is the peak height uncertainty and rmsd(noise) is the RMSD of the base plane noise. Tom Goddard added the RMSD calculation to Sparky (http://www.cgl.ucsf.edu/home/sparky/) - but I've still to thank him for adding that so quickly after I asked by giving him a citation. I don't know if other programs can calculate this RMSD value.
Ignoring the stuff with duplicate spectra, it's actually a rather nice situation with only peak height and baseline noise height being the information required for the calculation of NOE, R1, R2, and the propagation of their respective errors. Presumably this would then be enough to begin the model-free analysis in relax?
This would save NMR time and it would be sufficient for a model-free analysis if done carefully. Remember that the RMSD value in the random coil region is higher than the empty parts of the spectrum, so don't forget to get some estimates by measuring in there. Regards, Edward