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  • Description
  • Computes the Wilcoxon test (non-parametric test) on EP files (.p). It allows to compare 2 conditions (or the difference between 2 conditions) with paired subjects.


  • Usage
  • epwilcox [+fdr]
    with :

    • option :
      +fdr : computes False Detection Rate (FDR) after the statistical test. It creates 2 EP files with a mask of the statistical results (Z and p) with the computed FDR. This requires a probability (p) threshold value.

    This program uses an interactive input.The questions are as follows (questions (program) are italic, answers (user) are bold):
    Number of conditions (2 conditions or 1 = difference file) :
    2
    Number of files per condition :
    10
    FDR threshold :
    0.05
    It defines the probability (p) threshold value to be used for masking the statistical results (Z) by the threshold FDR statistics.
    Only if +fdr option is specified.

    Input file name (with extension) 1 in condition 1 :
    epfile1cond1.p
    Input file name (with extension) 2 in condition 1 :
    epfile2cond1.p
    ...
    Input file name (with extension) 1 in condition 2 :
    epfile1cond2.p
    ...
    Input file name (with extension) 10 in condition 0 :
    epfile10cond2.p

    Output file prefix (without extension) :
    wilcox_ep

  • Fields of parameter file and example

  • Examples

  • Comments
    1. The programs creates 2 EP files : .Z.p and .p.p . In the above example, it will give wilcox_ep.p.p and wilcox_ep_Z.p .
    2. All EP files should be compatible (in terms of number of channels and samples, number of pre-stimulus samples, sampling frequency) to the first EP file (file 1 in condition 1).


  • Current version
  • 2.06 17-07-2012

  • History
    • 1.00 08-04-2003 (PEA) : 1st documented version.
    • 2.00 22-05-2003 (PEA/OB) : adds the input of the difference between 2 conditions.
    • 2.01 13-08-2007 (PEA) : minor modification.
    • 2.02 29-09-2010 (PEA) : updates to use cmake and free release of Elan.
    • 2.03 02-02-2011 (PEA) : removes static allocation for reading and writing EP files.
    • 2.04 07-10-2011 (PEA) : adds test for at least 2 samples to test in Wilcoxon test.
    • 2.05 16-05-2012 (PEA) : adds FDR correction option.
    • 2.06 17-07-2012 (PEA) : fixes an error in wilcox function of libstat when all samples are ties.


  • Files
  • $ELANPATH/bin/epwilcox

  • See also
  • epquade, epkruskal, epwinquade