# [Eeglablist] paired t-test with corrected p-values

Carlos Mugruza cmugruza at yahoo.com
Mon Mar 15 08:01:17 PDT 2010

```Hello Michael,
I don't very sure if these could be 2 of your four answers:

1) I am not very sure what function you use to make the test. But I use ttest2, which gives you that you like: the fourth parameter is the tail (a flag), that specifies one of three alternative hypotheses:
tail = 0 (default) specifies the alternative,  only looks at the difference;
tail = 1 specifies the alternative, if the first is greater thant the second one;
tail = -1 specifies the alternative, if the first is less than the second one.

ttest2(x,y,alpha,tail)

4) I think is only change the axis. Eve you use a pre-exitent code, you can change it.

Regarding you question 3, really I don't understand very well. I imagine that it is take frequency vectors and do the test

Have a nice weekend.

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Carlos A. Mugruza V.
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School of Psychology
The University of Dundee
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Eeglablist] paired t-test with corrected p-valuesMichels Lars Lars.Michels at kispi.uzh.ch
Fri Mar 12 00:56:43 PST 2010

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Dear all,

I calculated in eeglab a paired t-test between two conditions with
corrected p-values (p < 0.05, FDR).

I used the study option for this and just tested it for two subjects,
just as a proof of principle

The panel on the right of the attached image shows the "significant"
differences between the two conditions.

However, I have four questions:

1) How do I know the direction of the statistical test, i.e. does the
grey regions indicate the significant differences for L2 > L5 or does
they simply show all significant differences (L2 > L5 and L5 > L2)?

2) Is it possible to plot the statistical map on the electrode level,
i.e. to see which electrodes reflecting the strongest effect?

3) Is it possible to calculate the test directly for predefined bands
(5-7 Hz etc)?

4) Why is the limit of the y-axis 0.1 and not 0.05. Is this because the
effects are always above 0.1?

Lars

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