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If you are extracting more than a single voxel, they will be different. If you have more than one group, then the variance correction in SPM will lead to different results as well. If you have the exact same design and variance settings AND extract a single voxel, the results will be the same. Any difference relates to the analysis being different in some aspect. Best Regards, Donald McLaren ================= D.G. McLaren, Ph.D. Research Fellow, Department of Neurology, Massachusetts General Hospital and Harvard Medical School Postdoctoral Research Fellow, GRECC, Bedford VA Website: http://www.martinos.org/~mclaren Office: (773) 406-2464 ===================== This e-mail contains CONFIDENTIAL INFORMATION which may contain PROTECTED HEALTHCARE INFORMATION and may also be LEGALLY PRIVILEGED and which is intended only for the use of the individual or entity named above. If the reader of the e-mail is not the intended recipient or the employee or agent responsible for delivering it to the intended recipient, you are hereby notified that you are in possession of confidential and privileged information. Any unauthorized use, disclosure, copying or the taking of any action in reliance on the contents of this information is strictly prohibited and may be unlawful. If you have received this e-mail unintentionally, please immediately notify the sender via telephone at (773) 406-2464 or email. On Fri, Oct 26, 2012 at 6:13 AM, Kristoffer Aberg <[log in to unmask]> wrote: > Dearest SPM experts, > > I want to correlate a score on a questionnaire with fMRI data. > The score is added as a parametric modulator on the second level and i > find some significant results. > > To visualize this using a scatterplot, values were extracted from the > .con images (for one voxel of interest) and correlated with the > questionnaire score. > The results are similar to those found using the SPM analysis. > > However, the p-values are only similar, but not exactly the same. > > The beta values were extracted by a script, by hand, and by the > marsbar toolbox - with identical results. > > Could someone please give me a hint of what im doing wrong and how i > should do it correctly? > > > Thank you in advance and have a good afternoon and weekend! > > Kristoffer