Dear Freesurfer Experts,
1) I have 2 groups (A & B), which do not differ in terms of gender ratio. If there were no significant regions for Group-Gender interaction in mean cortical thickness in the QDEC analysis, can I conclude that gender does not influence the effect of group on thickness? The differences between A and B on mean thickness is not affected by Gender? Is this valid or do I need to add Gender as a covariate even though the group do not differ on gender ratio?
2) A reviewer pointed that it is not right to test for group differences in volume once I have tested for thickness and area, especially when there is a cluster where A and B do not differ significantly in thickness and area but they differ significantly in volume...Is this right?
Please kindly advise.
Many thanks,
Lena
Dear Freesurfer Experts,
1) I have 2 groups (A & B), which do not differ in terms of gender ratio. If there were no significant regions for Group-Gender interaction in mean cortical thickness in the QDEC analysis, can I conclude that gender does not influence the effect of group on thickness? The differences between A and B on mean thickness is not affected by Gender? Is this valid or do I need to add Gender as a covariate even though the group do not differ on gender ratio?
2) A reviewer pointed that it is not right to test for group differences in volume once I have tested for thickness and area, especially when there is a cluster where A and B do not differ significantly in thickness and area but they differ significantly in volume...Is this right?
Please kindly advise.
Many thanks,
Lena
what do you mean they do not differ in gender ratio? Just that the relative number of M/F is the same in each group? If there is not a significant interaction between gender and group, then you can usually merge the genders.
On 04/05/2017 05:13 PM, Lim, Lena wrote:
Dear Freesurfer Experts,
- I have 2 groups (A & B), which do not differ in terms of gender
ratio. If there were no significant regions for Group-Gender interaction in mean cortical thickness in the QDEC analysis, can I conclude that gender does not influence the effect of group on thickness? The differences between A and B on mean thickness is not affected by Gender? Is this valid or do I need to add Gender as a covariate even though the group do not differ on gender ratio?
- A reviewer pointed that it is not right to test for group
differences in volume once I have tested for thickness and area, especially when there is a cluster where A and B do not differ significantly in thickness and area but they differ significantly in volume…Is this right?
Please kindly advise.
Many thanks,
Lena
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
Thanks, Doug.
There is no significant interaction and I merged the males and females within each group, but the reviewer wants me to include gender as a covariate. Do we always need to control for gender esp. when the group x gender is insignificant? Will that be "over-controlled"?
________________________________ From: freesurfer-bounces@nmr.mgh.harvard.edu freesurfer-bounces@nmr.mgh.harvard.edu on behalf of Douglas N Greve greve@nmr.mgh.harvard.edu Sent: 06 April 2017 20:45 To: freesurfer@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] QDEC-volume, thickness and area
what do you mean they do not differ in gender ratio? Just that the relative number of M/F is the same in each group? If there is not a significant interaction between gender and group, then you can usually merge the genders.
On 04/05/2017 05:13 PM, Lim, Lena wrote:
Dear Freesurfer Experts,
- I have 2 groups (A & B), which do not differ in terms of gender
ratio. If there were no significant regions for Group-Gender interaction in mean cortical thickness in the QDEC analysis, can I conclude that gender does not influence the effect of group on thickness? The differences between A and B on mean thickness is not affected by Gender? Is this valid or do I need to add Gender as a covariate even though the group do not differ on gender ratio?
- A reviewer pointed that it is not right to test for group
differences in volume once I have tested for thickness and area, especially when there is a cluster where A and B do not differ significantly in thickness and area but they differ significantly in volume…Is this right?
Please kindly advise.
Many thanks,
Lena
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.nmr....
-- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422
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probably so. It is up to you whether you want to fight the reviewer or not.
On 04/06/2017 05:08 PM, Lim, Lena wrote:
Thanks, Doug.
There is no significant interaction and I merged the males and females within each group, but the reviewer wants me to include gender as a covariate. Do we always need to control for gender esp. when the group x gender is insignificant? Will that be "over-controlled"?
*From:* freesurfer-bounces@nmr.mgh.harvard.edu freesurfer-bounces@nmr.mgh.harvard.edu on behalf of Douglas N Greve greve@nmr.mgh.harvard.edu *Sent:* 06 April 2017 20:45 *To:* freesurfer@nmr.mgh.harvard.edu *Subject:* Re: [Freesurfer] QDEC-volume, thickness and area what do you mean they do not differ in gender ratio? Just that the relative number of M/F is the same in each group? If there is not a significant interaction between gender and group, then you can usually merge the genders.
On 04/05/2017 05:13 PM, Lim, Lena wrote:
Dear Freesurfer Experts,
- I have 2 groups (A & B), which do not differ in terms of gender
ratio. If there were no significant regions for Group-Gender interaction in mean cortical thickness in the QDEC analysis, can I conclude that gender does not influence the effect of group on thickness? The differences between A and B on mean thickness is not affected by Gender? Is this valid or do I need to add Gender as a covariate even though the group do not differ on gender ratio?
- A reviewer pointed that it is not right to test for group
differences in volume once I have tested for thickness and area, especially when there is a cluster where A and B do not differ significantly in thickness and area but they differ significantly in volume…Is this right?
Please kindly advise.
Many thanks,
Lena
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu
https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.nmr....
-- 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://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgate.nmr.... https://emea01.safelinks.protection.outlook.com/?url=www.nmr.mgh.harvard.edu... Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmail.nmr....
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 https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.partne... . 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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Douglas N Greve -
Lim, Lena