New statistics

[Vladimir Litvak]

Hi Robert,

Stupid mistake indeed, but even after fixing it the results are not the
same. There is a very nice big positive cluster in the gamma range I get
with clusterrandanalysis that is completely absent in the new result. Since
the effect is pretty clear in the raw data I think there is still a problem.


Please run the fixed version with and compare the old results with new.

Thanks,

Vladimir

-----Original Message-----
From: FieldTrip discussion list [mailto:FIELDTRIP at NIC.SURFNET.NL] On Behalf
Of Robert Oostenveld
Sent: Wednesday, February 07, 2007 8:44 PM
To: FIELDTRIP at NIC.SURFNET.NL
Subject: Re: [FIELDTRIP] New statistics

Hi Vladimir,

On 30 Jan 2007, at 18:37, Vladimir Litvak wrote:
> I'm trying to switch from clusterrandanalysis to the new statistics
> routines. I made my best to configure the new routine in a way that
> would yield results identical to the old routine, but the results I
> get are very different. I put an example athttp://
> download.yousendit.com/7CE5F69B35B1C739 . Please check what's going
> on.

I looked in the script and data that you have sent and notice that

 >> cfg.design
ans =
      1     2     3     4     5     6     7     8     9    10
11     1     2     3     4     5     6     7     8     9    10    11
      1     1     1     1     1     1     1     1     1     1
1     2     2     2     2     2     2     2     2     2     2     2
 >> size(cfg.design)
ans =
      2    22

and furthermore

 >> size(freqavg{1}.powspctrm)
ans =
     22     1    50   965
 >> size(freqavg{2}.powspctrm)
ans =
     22     1    50   965

So even though you seem to have 22+22=44 observations/subjects in the
data, you are only using 22 in the design to compute your statistical
contrast: You are actually computing the contast between the first 11
subjects in the first condition versus the second 11 subjects in the
first condition.

Your design probably should be
cfg.design = [
   1:22         1:22             % subject index, runs from 1 to 22
(twice, since paired data)
   1*ones(1,22) 2*ones(1,22)     % condition number, is either 1 or 2
];

best regards,
Robert