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It should in fact be a ttest however what I was trying to do was use dual regression on my melodic output. My matrix wasn't working because it didn't match the number of inputs. I have 10 melodic outputs (1 per person) and haven't been able to design a matrix that would take into account the two conditions within the output. I can only do that in FEAT wig custom EVs. So far he only thing I've been able to come up with is to cut my files so that the melodic outputs are broken down by video type and then compare between men and women using dual regression.

May

Sent from my iPad

On Jan 29, 2015, at 4:50 AM, Anderson M. Winkler <[log in to unmask]> wrote:

Hi Mayte,

This design is fine on what concerns running dual_regression and randomise. There may be something else going on there. Try perhaps with a small set of subjects first, making sure you follow the steps in the manual, etc.

That said, I thought from earlier emails that each subject had been scanned under both conditions (H and E), so it sounds like a paired t-test would be needed.

All the best,

Anderson


2015-01-27 15:43 GMT+00:00 Mayte Parada, Ms. <[log in to unmask]>:
Hi Anderson,

After creating my design.mat and design.con files using FEAT I’ve run them through dual_regression and I don’t see the full complement of files that I’m supposed to. I’m wondering if the design files are incorrect?


Design.con file looks like this. I have two conditions in my 1 scan (humour vs erotic) and two groups of subjects (men & women) so I’ve tried to indicate the contrasts here:
/ContrastName1 W>M_Humour 
/ContrastName2 M>W_Humour 
/ContrastName3 W>M_Erotic 
/ContrastName4 M>W_Erotic 
/ContrastName5 H_mean 
/ContrastName6 E_mean 
/NumWaves 4
/NumContrasts 6
/PPheights 1.000000e+00 1.000000e+00 1.000000e+00 1.000000e+00 5.000000e-01 5.000000e-01
/RequiredEffect 3.758 3.758 3.758 3.758 1.879 1.879

/Matrix
1.000000e+00 -1.000000e+00 0.000000e+00 0.000000e+00 
-1.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00 
0.000000e+00 0.000000e+00 1.000000e+00 -1.000000e+00 
0.000000e+00 0.000000e+00 -1.000000e+00 1.000000e+00 
1.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00 
0.000000e+00 0.000000e+00 1.000000e+00 1.000000e+00 



Design.mat file looks like this. Here I try to indicate who are the women and who are the men by using the cope files that I got from the first level feat in the Humour mean (H_mean) and Erotic mean (E_mean) from above.
/NumWaves 4
/NumPoints 20
/PPheights 1.000000e+00 1.000000e+00 1.000000e+00 1.000000e+00

/Matrix
1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00
1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00
1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00
1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00
1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00
0.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00
0.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00
0.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00
0.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00
0.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00
0.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00
0.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00
0.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00
0.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00
0.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00
0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00
0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00
0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00
0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00
0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00








--
Mayte Parada Ph.D.
____________________________
Laboratory for the Biopsychosocial Study of Sexuality
McGill University
1205 Docteur Penfield 
Montreal QC
Canada H3A 1B1
[log in to unmask]
On Jan 22, 2015, at 10:23 AM, Mayte Parada, Ms. <[log in to unmask]> wrote:
Thanks Anderson,

I completely understand now. Found the cope images in the stats folders and will input the ones that represent each video type. Then I will identify men and women into the EVs for the higher level analysis and contrast them.
Thanks!
--
Mayte Parada Ph.D.
____________________________
Laboratory for the Biopsychosocial Study of Sexuality
McGill University
1205 Docteur Penfield 
Montreal QC
Canada H3A 1B1
[log in to unmask]
On Jan 21, 2015, at 4:45 PM, Anderson M. Winkler <[log in to unmask]> wrote:

Hi Mayte,

You can do a 2nd level between erotic and humour, even if these two conditions are in the same run, as long as they were coded at the lower level with separate EVs, which would give one COPE for each of these two conditions. These can then be compared at the 2nd level with a paired t-test.

Alternatively, compare these two conditions still within the 1st level, then in the 2nd level select these FEAT directories for a comparison men vs. women. Note that for the effect of sex, even if the groups happen to be matched, it's a simple 2-sample t-test that needs to be done, i.e., not a paired t-test.

All the best,

Anderson


2015-01-21 20:06 GMT+00:00 Mayte Parada, Ms. <[log in to unmask]>:
Thanks Anderson,

Yes I can do a higher level analysis between men and women using their FEAT directories. That’s fairly straight forward. 

Its when I try to distinguish between men and women, and erotic movie vs humour movie….since both movies are played in the same run. I don’t have separate FEAT outputs for the movie types to enter for each participant. I don’t know how to generate those if each participant has two conditions/movies within the same run.

--
Mayte Parada Ph.D.
____________________________
Laboratory for the Biopsychosocial Study of Sexuality
McGill University
1205 Docteur Penfield 
Montreal QC
Canada H3A 1B1
[log in to unmask]

On Jan 21, 2015, at 10:36 AM, Anderson M. Winkler <[log in to unmask]> wrote:

Hi Mayte,

Not sure if I follow, but it's fine to do a paired t-test on the outputs from 1st level FEAT. You wouldn't enter the same information twice, though. Perhaps the best choice would be if you selected the option "Inputs are 3D cope images from FEAT directories".

All the best,

Anderson


2015-01-20 23:23 GMT+00:00 Mayte Parada, Ms. <[log in to unmask]>:
Hi experts,

I’m trying to run a paired ttest and I want to make sure I understand the wiki properly.

I have one run/trial/scan (the terms are a bit confusing so I want to be clear) and there are two conditions within the trial (humour vs erotic). I already did a lower level feat for each subject in the experiment and gathered the individual feat outputs (10 in total). I want to compare activation in the humour condition with the erotic condition for those subjects. I am now using higher-level analysis to do a paired test based on the wiki. I’ve entered the lower level feat files twice to get 20 input files and made an EV for each of the participants and an extra EV for comparing the trials.
For some reason this doesn’t feel right.

my EVs and contrasts look like the example provided in the wiki but I’m not 100% about the feat files i’m entering. I had 10 participants but I’m comparing them with themselves for a paired test so I have to enter the feat files 2x correct?



--
M