Reply-To: | | [log in to unmask][log in to unmask] <mailto:[log in to unmask]> >> > <mailto:[log in to unmask] <mailto:[log in to unmask]>>>: >> > >> > Dear Matthieu, >> > >> > the function you are looking at concerns first level fMRI so >> for PET >> > 'basic' models, you need to look at >> > spm12/config/spm_run_factorial_design.m >> > When using proportional scaling global normalisation, the >> global scaling >> > factor, gSF, is computed l.838 and applied to the data l.855. >> > >> > Best regards, >> > Guillaume. >> > >> > >> > On 18/12/15 15:33, Matthieu Vanhoutte wrote: >> > > Dear SPM experts, >> > > >> > > I have been searching for explicit formula of the global >> normalization >> > > with proportional scaling as it is used in SPM. I have found >> this code >> > > in "spm_fmri_spm_ui.m" : >> > > >> > > /%-Compute Global variate >> > > >> > >> %========================================================================== >> > > GM = 100; >> > > q = length(VY); >> > > g = zeros(q,1); >> > > fprintf('%-40s: ','Calculating globals') >> > %-# >> > > spm_progress_bar('Init',q,'Calculating globals'); >> > > if spm_mesh_detect(VY) >> > > for i = 1:q >> > > dat = spm_data_read(VY(i)); >> > > g(i) = mean(dat(~isnan(dat))); >> > > spm_progress_bar('Set',i) >> > > end >> > > else >> > > for i = 1:q >> > > g(i) = spm_global(VY(i)); >> > > spm_progress_bar('Set',i) >> > > end >> > > end >> > > spm_progress_bar('Clear'); >> > > fprintf('%30s\n','...done') >> > %-# >> > > >> > > %-Scale if specified (otherwise session specific grand mean >> scaling) >> > > >> > >> %-------------------------------------------------------------------------- >> > > gSF = GM./g; >> > > if strcmpi(SPM.xGX.iGXcalc,'none') >> > > for i = 1:nsess >> > > gSF(SPM.Sess(i).row) = GM./mean(©¸¨M |