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  • Description
  • Computes the Kruskal-Wallis (non-parametric test) test between several groups (conditions) of EP files (.p). The output are statistical EP files. The statistical procedure is described in “Non Parametric Statistics for the Behavioural Sciences” by S. Siegel, McGraw Hill, 1956, p.184.

  • Usage
  • epkruskal [+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 (H 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):
FDR threshold :
0.05
It defines the probability (p) threshold value to be used for masking the statistical results (H) by the threshold FDR statistics.
Only if +fdr option is specified.
Number of conditions :
3
Number of files in condition 1 :
10
Number of files in condition 2 :
15
Number of files in condition 3 :
12
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) 12 in condition 3 :
epfile12cond3.p
Output file name (without extension) :
out_ep.kw

  • Fields of parameter file and example

  • Examples
  • The example above will create the following files :
    out_ep.kw.H.p : .p file of the H value of the Kruskal-Wallis test computed on the 3 conditions.
    out_ep.kw.p.p : .p file of the probability value (p) of the Kruskal-Wallis test computed on the 3 conditions.

  • Comments
    1. 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
  • 1.04 29-06-2012

  • History
    • 1.00 09-04-2005 (OB) : 1st documented version.
    • 1.01 13-08-2007 (PEA) : minor modification.
    • 1.02 29-09-2010 (PEA) : updates to use cmake and free release of Elan.
    • 1.03 26-01-2011 (PEA) : removes static allocation for reading and writing EP files.
    • 1.04 29-06-2012 (PEA) : adds FDR correction option.


  • Files
  • $ELANPATH/bin/epkruskal

  • See also
  • epwilcox, epquade, epwinquade