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help > RE: Design Matrix and Contrast
Jul 21, 2018 12:07 AM | Andrew Zalesky
RE: Design Matrix and Contrast
Hi Anita,
you wrote "I ran a paired two-sample means test to compare the changes in significant connections between group 1 and group 2"
But this seems to contradict the fact the you did not find any significant connections between group 1 and group 2.
Note that the one-sample test will not test for differences between the groups. It will just tell you whether the connection weight is significantly different from zero.This has nothing to do with a between group difference.
It is also unclear how you corrected for multiple comparisons in Excel. Did you run a t-test separately for each connection (this requires correction for multiple comparisons), or did you run a t-test on some kind of average across connections?
In general, a paired t-test will paired t-test will offer greater power in this situation.
Andrew
Originally posted by asinha:
you wrote "I ran a paired two-sample means test to compare the changes in significant connections between group 1 and group 2"
But this seems to contradict the fact the you did not find any significant connections between group 1 and group 2.
Note that the one-sample test will not test for differences between the groups. It will just tell you whether the connection weight is significantly different from zero.This has nothing to do with a between group difference.
It is also unclear how you corrected for multiple comparisons in Excel. Did you run a t-test separately for each connection (this requires correction for multiple comparisons), or did you run a t-test on some kind of average across connections?
In general, a paired t-test will paired t-test will offer greater power in this situation.
Andrew
Originally posted by asinha:
Andrew,
I will clarify my previous post below.
Given that I did not find statistical significance in NBS when running a paired t-test between group 1 (before) and group 2 (after), I ran one-sample t-tests on my 26 subjects using the following design matrix:
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
to identify the most significant connections between ROIs for group 1 and again for group 2.
Then, in Excel, I ran a paired two-sample means test to compare the changes in significant connections between group 1 and group 2 and got a p-value = 6.40*10^-5.
My question is: how is this different than running a paired t-test in NBS that accounts for repeated measures with the first design matrix in my original post? When I run that, I get a p-value of 1.0.
Regards,
Anita
I will clarify my previous post below.
Given that I did not find statistical significance in NBS when running a paired t-test between group 1 (before) and group 2 (after), I ran one-sample t-tests on my 26 subjects using the following design matrix:
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
to identify the most significant connections between ROIs for group 1 and again for group 2.
Then, in Excel, I ran a paired two-sample means test to compare the changes in significant connections between group 1 and group 2 and got a p-value = 6.40*10^-5.
My question is: how is this different than running a paired t-test in NBS that accounts for repeated measures with the first design matrix in my original post? When I run that, I get a p-value of 1.0.
Regards,
Anita
Threaded View
Title | Author | Date |
---|---|---|
asinha | Jul 17, 2018 | |
Andrew Zalesky | Jul 18, 2018 | |
asinha | Jul 18, 2018 | |
Andrew Zalesky | Jul 18, 2018 | |
asinha | Jul 19, 2018 | |
Andrew Zalesky | Jul 21, 2018 | |