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. Author manuscript; available in PMC: 2014 Oct 30.
Published in final edited form as: Neuroimage. 2014 Jan 8;91:412–419. doi: 10.1016/j.neuroimage.2013.12.058

Fig. 2.

Fig. 2

(A) A contour map of cluster extent size (k) for FWER corrected p < .05 (based on cluster-extent thresholding using Gaussian random field method implemented in SPM) as a function of primary threshold (z) and the intrinsic smoothness level (FWHM in voxels). Arrows indicate the three most popular primary threshold levels, p < .01 (z = 2.33), p < .005 (z = 2.58), and p < .001 (z = 3.09), from left to right. Horizontal dashed lines indicate intrinsic smoothness levels from 9 fMRI studies from Nichols & Hayasaka (2003). (B) The proportions of studies using each level of cluster-defining primary p-value across fMRI analysis software packages. The error bars represent standard error of the mean (S.E.M.) using a binomial distribution. The default setting of primary threshold is .001 in SPM and .01 in FSL. BV = Brain Voyager. Others includes Freesurfer, fMRISTAT, LIPSIA, XBAM, and papers that do not specify the software. nAFNI = 57, nBV = 43, nFSL = 69, nSPM = 298, and nOthers = 17.

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