7.1.422. fdrval

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Usage: fdrval [options] dset sub val [val ...]

Reads FDR curve data from the header of dset for sub-brick #sub and computes the q-value when the sub-brick statistical threshold is set to val.

OPTIONS

-pval = also output the p-value (on the same line, after q)
-ponly = don’t output q-values, just p-values
-qonly = don’t output p-values, just q-values [the default]
-qinput = The ‘val’ inputs are taken to be q-values and then the
OR outputs are the corresponding statistical thresholds.
-inverse This is the inverse of the usual operation.
  • With this option, all ‘val’ inputs must be between 0 and 1 (exclusive), or bad things will happen and the program will send e-mail to your mother explaining how stupid you are.

  • You cannot use ‘-ponly’ or ‘-pval’ with this option.

  • For example, if you do

    fdrval dset+orig 1 1.2

    and get a q-value of 0.234, then

    fdrval -qinput dset+orig 1 0.234

    should return the value 1.2 – the original threshold. (There may be a small discrepancy, due to the differences) (between forward interpolation and inverse interpolation.)

  • To set a (csh) variable to use in a script for thresholding via 3dcalc, you could do something like

    set tval = fdrval -qinput dset+orig 1 0.05 3dcalc -expr “step(a-$tval)” -a dset+orig’[1]’ -prefix dmask

NOTES

  • Output for each ‘val’ is written to stdout.

  • If the q-value can’t be computed, then 1.0 will be output.

  • If you input an absurdly high threshold, you will get the smallest

    q-value stored in the dataset header. (This is not necessarily exactly the smallest q-value that was computed originally, due to the way the FDR curves are calculated and interpolated.)

  • If you use ‘-qinput’ and input a q-value that is too small for the

    FDR curve in the dataset header, you will get a threshold at or above the largest value in that sub-brick.

  • Sample usage:

    fdrval Fred_REML+orig 0 count -scale 0.1 10 20 | 1dplot -stdin

    Uses the ‘count’ program to input a sequence of values, and then pipes into the 1dplot program to make a graph of F vs. q.

  • See the link below for information on how AFNI computes FDR curves:

    http://afni.nimh.nih.gov/pub/dist/doc/misc/FDR/FDR_Jan2008.pdf

  • Also see the output of ‘3dFDR -help’

– A quick hack by RWCox – 15 Oct 2008 – PG Wodehouse’s birthday! – Quick re-hack to add ‘-qinput’ option – 20 Dec 2011 – RWCox – Re-re-hack to make super-small ‘-qinput’ values work right – 14 Mar 2014

++ Compile date = Dec 16 2015

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