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  • Description
  • Performs a statistical randomization test without replacement between k conditions from single-trials stored in an EEG file. This program is very similar to eegranddiff. It compares the sum of the first 2 conditions against the third condition.

  • Usage
  • eegrandadd myeegfile.eeg myposfile.pos myparfile.par nb_drawings

    with :

    • myeegfile.eeg : input EEG file to process (with extension).
    • myposfile.pos : event position file.
    • myparfile.par : parameter file, similar to that used for eegavg, but with some additional parameters.
    • nb_drawings : number of drawings that are made to estimate the distribution of differences under the null hypothesis (example: 10000 drawings enables a resolution of p=0.0001).


  • Fields of parameter file and example
  • fileprefix myfilename Prefix of the output .p files.
    nb_eventcode 2 Number of event codes to process.
    list_eventcode 2 5 List of the event codes to process.
    prestim_nbsample 400 400 List of the numbers of samples in the prestimulus period; one value for each event code.
    poststim_nbsample 800 800 List of the numbers of samples in the poststimulus period; one value for each event code; the total number of samples of the analysis is prestim_nbsample + poststim_nbsample + 1, the extra sample corresponds to the event itself
    ep_channel_flag 1 1 0 1 0 0 0 List of the channels to average: 1/0 for selected/unselected channels; the total number of flags is N+2, N being the number of recorded channels in myeegfile.eeg file; the last 2 flags should be set to 0.
    In this example, N=5, and only channels number 1, 2, 4 will be averaged and stored in the output .p files.
    ep_channel_ref 0 5 0 6 0 0 0 List of the new reference for each channel before averaging (bipolar montage for instance):
    0: no change of the reference,
    ≠0: electrode number (rank) to which the current channel should be re-referenced.
    The total number of values is N+2, N being the number of recorded channels in myeegfile.eeg file; the last 2 flags should be set to 0.
    This field is optional. If omitted, the channels are not modified.
    In this example, N=5, and channel 1 is unchanged, channel 2 is referenced to channel 5, and channel 4 re-referenced to channel 6.
    eegranddiff_baseline_eventcode 2 2 List of the event codes used to compute the baseline.
    0: no baseline correction (default),
    ≠0: event code on which baseline will be computed.
    In this example, the baseline for event code 2 will be computed from event code 2, and the baseline of event code 5 from event code 2.
    Warning: the event-code should be chosen among those listed in list_eventcodes.
    This field is optional.
    eegranddiff_baseline_msec_start -300 -300 List of the baseline start latencies (in ms); one value for each event code; required only if baseline_eventcode≠0.
    If omitted and baseline_eventcode≠0, the baseline value is computed on the whole epoch.
    eegranddiff_baseline_msec_stop -100 -100 List of the baseline stop latencies (in ms); one value for each event code; required only if baseline_eventcode≠0.
    If omitted and baseline_eventcode≠0, the baseline value is computed on the whole epoch.
    eegranddiff_time_hw 200 200 200 List of the time half-windows (in ms) by event code, used to defined the moving time-window on which statistical analysis will be performed.
    If omitted, no smoothing is applied and computation is performed on each time-sample.
    eegranddiff_time_step 50 50 50 List of the time steps (in ms) by event code, used to defined the moving step of the moving time-window on which statistical analysis will be performed.
    If omitted, the time step is one sample.
    eegranddiff_measure 1 Statistic on which the permutation test will be made :
    1: Sum of squared sums of values by conditions (two-sided test)
    2: Sum of values in the first condition (one-sided test), valid only if k=2 conditions.
    If omitted, default value is 1.
    eegranddiff_compute 1 Choice for multiple test correction :
    0: no multiple test correction
    1: multiple test correction based on the maximum number of consecutive samples
    2: multiple test correction based on the minimum significance across samples
    3: same as 2 across samples and channels
    If omitted, default value is 0 (no correction).
    eegranddiff_proba_measure 0.05 If eegrandiff_compute = 1, statistical probability threshold for the determination of significant samples.
    eegranddiff_proba_compute 0.05 If eegrandiff_compute ≥ 1, statistical probability threshold for the computation of consecutive significant sample.
    eegranddiff_compute_msec_start 50 If eegrandiff_compute ≥ 1, start latency (in msec) of the analysis window for the correction across samples.
    eegranddiff_compute_msec_stop 50 If eegrandiff_compute ≥ 1, stop latency (in msec) of the analysis window for the correction across samples.
    erpa_positivity_up 1 Value stored in all output .p file to set the default upward/downward positivity orientation for curve display (by erpa).
    -1 (positivity down) or 1 (positivity up)
    This field is optional. If omitted, erpa will display curve with positivity down.
    erpa_view 4 Value stored in all output .p file. It is used by erpa to set the default mapping view.
    1: right view
    2: left view
    3: top view
    4: back view
    5: large top view
    6: back-top view
    This field is optional. If omitted, it is set to 0, and erpa default will be top view.



  • Examples


  • Comments
    • See eegchref to create a re-referenced .eeg data file (several referencing options available).


  • Current version
  • 1.11 15-04-2011

  • History
    • 1.01 30-06-2006 (JB) : 1st version, derived from eegranddiff v 2.01 .
    • 1.02 02-07-2006 (JB) : fixes smoothing (compatible with eegstat).
    • 1.03 03-07-2006 (JB) : fixes baseline correction.
    • 1.04 05-07-2006 (JB) : adds compute_msec_start and compute_msec_stop to have independant analysis window and baseline window.
    • 1.05 06-07-2006 (JB) : optimizes computing with copy of data out of permutations loop.
    • 1.06 11-12-2006 (JB) : fixes bilateral statistic (see eegranddiff).
    • 1.07 24-01-2007 (JB) : fixes for event numbers. Adds unilateral test.
    • 1.08 26-01-2007 (JB) : modifies decision for loading data to memory (if data size<= whole memory, not just available).
    • 1.09 26-01-2007 (JB) : removes count of n_max out of window.
    • 1.10 28-09-2010 (PEA) : update to use cmake and free release of Elan. Changes for parameter names : compute_msec_start and compute_msec_stop become eegranddiff_compute_msec_start and eegranddiff_compute_msec_stop. Changes for baseline parameters : baseline_eventcode, baseline_msec_start and baseline_msec_stop become eegranddiff_baseline_eventcode, eegranddiff_baseline_msec_start and eegranddiff_baseline_msec_stop.
    • 1.11 15-04-2011 (PEA) : changes Shell sort to Heap sort in FDR (faster algorithm).


  • Files
  • $ELANPATH/bin/eegrandadd

  • See also
  • eegranddiff, eegstat, eegavg, eegchref