Dear freesurfers, I want to look at the gender differences of a correlation between cortical thickness and some impulsivity-tests. When I use qdec, the question "Does the thickness-BIS-correlation differ between 0 and 1?" is displayed. So, 0 and 1 are female/male. But there are positive and negative correlations (red and blue voxels)...what does it mean? There can not be a negative difference...?? Thank you very much! Leni
Hi Lena, it is not a difference, it is a correlation between thickness and BIS. The sentence produced by QDEC would be clearer if you gave the groups actual names instead of 0 and 1. doug
On 04/22/2013 04:46 AM, Hélène Bretschneider wrote:
Dear freesurfers, I want to look at the gender differences of a correlation between cortical thickness and some impulsivity-tests. When I use qdec, the question "Does the thickness-BIS-correlation differ between 0 and 1?" is displayed. So, 0 and 1 are female/male. But there are positive and negative correlations (red and blue voxels)...what does it mean? There can not be a negative difference...?? Thank you very much! Leni
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Dear Doug,
Thank you very much for your help. Unfortunately, I'm still confused about these questions...First, I wanted to see the correlation between cortical thickness and BIS (an impulsivity-test), corrected for age and gender. Therefore, I chose this question : "Does the correlation between thickness and BIS-total, accounting for gender, differ from zero. Nuisance factor: age". Is that wrong...?
Then, I wanted to look at the differences in this correlation between males and females. Therefore, I chose: "Does the thickness-BIS-correlation differ between 0 and 1?" (male and female....yes I have to change the numbers ind male and female!)
I read the qdec- tutorial and found "....Does the Thickness--age correlation differ between male and female?... Click on this question to display the statistically significant regions where the age and thickness correlation are different in men and women..." (http://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/QdecGroupAnalysis).
And that would be what I try to find. I want to see if females and males have differences in the thickness-BIS-correlation. And I do not understand why qdec displays negative and positive values for this question. And if this question only mean the correlation (without the correction for age..?), I wonder how to see gender differences.
Could you explain me how to see the gender differences?
Thank you!
Leni
Am 22.04.2013 um 15:56 schrieb Douglas N Greve greve@nmr.mgh.harvard.edu:
Hi Lena, it is not a difference, it is a correlation between thickness and BIS. The sentence produced by QDEC would be clearer if you gave the groups actual names instead of 0 and 1. doug
On 04/22/2013 04:46 AM, Hélène Bretschneider wrote:
Dear freesurfers, I want to look at the gender differences of a correlation between cortical thickness and some impulsivity-tests. When I use qdec, the question "Does the thickness-BIS-correlation differ between 0 and 1?" is displayed. So, 0 and 1 are female/male. But there are positive and negative correlations (red and blue voxels)...what does it mean? There can not be a negative difference...?? Thank you very much! Leni
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-- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422
Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/
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Hi Leni, for each group you get a correlation between BIS and thickness. If the correlation in the males is greater than that in the females, you will get a positive difference. If the correlation in the males is lessthan that in the females, you will get a negative difference. doug
On 04/22/2013 02:07 PM, Hélène Bretschneider wrote:
Dear Doug,
Thank you very much for your help. Unfortunately, I'm still confused about these questions...First, I wanted to see the correlation between cortical thickness and BIS (an impulsivity-test), corrected for age and gender. Therefore, I chose this question : "Does the correlation between thickness and BIS-total, accounting for gender, differ from zero. Nuisance factor: age". Is that wrong...?
Then, I wanted to look at the differences in this correlation between males and females. Therefore, I chose: "Does the thickness-BIS-correlation differ between 0 and 1?" (male and female....yes I have to change the numbers ind male and female!)
I read the qdec- tutorial and found "....Does the Thickness--age correlation differ between male and female?... Click on this question to display the statistically significant regions where the age and thickness correlation are different in men and women..." (http://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/QdecGroupAnalysis).
And that would be what I try to find. I want to see if females and males have differences in the thickness-BIS-correlation. And I do not understand why qdec displays negative and positive values for this question. And if this question only mean the correlation (without the correction for age..?), I wonder how to see gender differences.
Could you explain me how to see the gender differences?
Thank you!
Leni
Am 22.04.2013 um 15:56 schrieb Douglas N Greve <greve@nmr.mgh.harvard.edu mailto:greve@nmr.mgh.harvard.edu>:
Hi Lena, it is not a difference, it is a correlation between thickness and BIS. The sentence produced by QDEC would be clearer if you gave the groups actual names instead of 0 and 1. doug
On 04/22/2013 04:46 AM, Hélène Bretschneider wrote:
Dear freesurfers, I want to look at the gender differences of a correlation between cortical thickness and some impulsivity-tests. When I use qdec, the question "Does the thickness-BIS-correlation differ between 0 and 1?" is displayed. So, 0 and 1 are female/male. But there are positive and negative correlations (red and blue voxels)...what does it mean? There can not be a negative difference...?? Thank you very much! Leni
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu mailto:Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
-- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu mailto:greve@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422
Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail.
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
freesurfer@nmr.mgh.harvard.edu
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Hélène Bretschneider