vbperminfo
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vbperminfo examines a directory full of stat cubes and creates a distribution for use in a permutation test. The options for what distribution to tally are listed below in the help text:
VoxBo vbperminfo (v1.8.5/Jun 14 2011)
summary: display information about permutation testing results
usage:
vbperminfo -c <dir> <outfile> <thresh> <alpha> <mask>
creates a distribution of max cluster size
vbperminfo -p <stem> <outfile> <alpha>
creates a distribution of peak values
vbperminfo -u -t <truevol> -i <iterationdir> -o output
vbperminfo -r <file> [alpha]
calculates criteria for an existing ResultValues.ref
vbperminfo -k <stem> <outfile> <clustersize> <alpha>
creates a distribution for cluster-corrected thresholds
vbperminfo -d <dist> <stat value>
vbperminfo -dr <dist> <stat value or ref>
other usage (these options may be outdated)
vbperminfo -pm [-a <alpha>] [-m <mask>] [-o <outfile>] <dir> <dir> ...
creates a distribution for peak minimum values across multiple maps
the result is stored in outfile and sampled at alpha (default 0.05)
notes:
The -p and -u options will accept a directory, filename, or stem as
the data source. A stem is just the part of the filename shared by
all the permutation volumes. E.g., "permdir/cube" matches all files
in permdir that begin with "cube". The -c and -k options currently
require a stem (will be fixed soon).
The -pm option can be slow and use up a lot of memory. Only use it
if you're sure you need it.
The -u option calculates a separate permutation test in each voxel
(using the same set of permutations) and produces three maps (in a
single 4D volume). The first is the p map, the second is a map of
the original stat values, and the third contains Z scores (converted
from the p values).
The -d option takes a vector file that contains a distribution of
values, and a stat value of interest, and returns a p value
corresponding to the proportion of values in the distribution
meeting or exceeding that value. -dr returns the proportion of
values <= the value you pass.
The -r option allows you to examine existing ResultValues.ref files,
trying out different alpha values.
Note that the reported thresholds must be *exceeded* -- i.e., if the
results file tells you that an alpha of 0.05 requires a threshold of
t=3.17, voxels with a value of t=3.17 do not meet this standard.
This is particularly important in cases where the permutation
distribution may have duplicate values.
