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We are using a paired analysis approach to study cortical thickness in a dataset with 2 timepoints (called pre-protocol and post-protocol). Regarding the mean cluster summary (contrast: [1 0]), we understand positive values to mean pre > post (thinning) and negative values to mean post > pre (thickening). The covariate results are more difficult to interpret. For instance, we’re interested in looking at the effects of age (contrast: [0 1]) on the cortical thickness results. In the age cluster summary, is it fair to interpret positive results as positive correlation (older subjects show more thickening) and negative results as inverse correlation (older subjects show more thinning) or is the interpretation more complex than this? We’re getting mainly negative cluster results for age so this interpretation may make sense, but we’d like more clarity. Thank you for your help.
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Hello all - reposting this to see if anyone can help - thanks!
We are using a paired analysis approach to study cortical thickness in a dataset with 2 timepoints (called pre-protocol and post-protocol). Regarding the mean cluster summary (contrast: [1 0]), we understand positive values to mean pre > post (thinning) and negative values to mean post > pre (thickening). The covariate results are more difficult to interpret. For instance, we’re interested in looking at the effects of age (contrast: [0 1]) on the cortical thickness results. In the age cluster summary, is it fair to interpret positive results as positive correlation (older subjects show more thickening) and negative results as inverse correlation (older subjects show more thinning) or is the interpretation more complex than this? We’re getting mainly negative cluster results for age so this interpretation may make sense, but we’d like more clarity. Thank you for your help.
Doug M
On Tue, Nov 30, 2021 at 10:04 AM PDMD SRALab sralab.pdmd@gmail.com wrote:
We are using a paired analysis approach to study cortical thickness in a dataset with 2 timepoints (called pre-protocol and post-protocol). Regarding the mean cluster summary (contrast: [1 0]), we understand positive values to mean pre > post (thinning) and negative values to mean post > pre (thickening). The covariate results are more difficult to interpret. For instance, we’re interested in looking at the effects of age (contrast: [0 1]) on the cortical thickness results. In the age cluster summary, is it fair to interpret positive results as positive correlation (older subjects show more thickening) and negative results as inverse correlation (older subjects show more thinning) or is the interpretation more complex than this? We’re getting mainly negative cluster results for age so this interpretation may make sense, but we’d like more clarity. Thank you for your help.
Can you say more about your approach? Are you subtracting the two time points explicitly and computing a paired t? Or are you using the repeated measures anova approach. Send the FSGD file
On 11/30/2021 11:04 AM, PDMD SRALab wrote:
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We are using a paired analysis approach to study cortical thickness in a dataset with 2 timepoints (called pre-protocol and post-protocol). Regarding the mean cluster summary (contrast: [1 0]), we understand positive values to mean pre > post (thinning) and negative values to mean post > pre (thickening). The covariate results are more difficult to interpret. For instance, we’re interested in looking at the effects of age (contrast: [0 1]) on the cortical thickness results. In the age cluster summary, is it fair to interpret positive results as positive correlation (older subjects show more thickening) and negative results as inverse correlation (older subjects show more thinning) or is the interpretation more complex than this? We’re getting mainly negative cluster results for age so this interpretation may make sense, but we’d like more clarity. Thank you for your help.
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
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We are using the paired analysis approach as outlined here ( https://secure-web.cisco.com/13QTl-VyyAVXvg-0pygxBoVuOM74Yxhp2T1X_88Q9Q9Lh3Z...) so yes we are subtracting the two time points explicitly and computing a paired t-test as you suggested. I've attached both the first fsgd file (pairs.fsgd) and the second fsgd file (paired-diff.fsgd) for your reference. Thanks for the help! - Doug M
On Fri, Dec 10, 2021 at 5:49 PM Douglas N. Greve dgreve@mgh.harvard.edu wrote:
Can you say more about your approach? Are you subtracting the two time points explicitly and computing a paired t? Or are you using the repeated measures anova approach. Send the FSGD file
On 11/30/2021 11:04 AM, PDMD SRALab wrote:
External Email - Use CautionWe are using a paired analysis approach to study cortical thickness in a dataset with 2 timepoints (called pre-protocol and post-protocol). Regarding the mean cluster summary (contrast: [1 0]), we understand positive values to mean pre > post (thinning) and negative values to mean post > pre (thickening). The covariate results are more difficult to interpret. For instance, we’re interested in looking at the effects of age (contrast: [0 1]) on the cortical thickness results. In the age cluster summary, is it fair to interpret positive results as positive correlation (older subjects show more thickening) and negative results as inverse correlation (older subjects show more thinning) or is the interpretation more complex than this? We’re getting mainly negative cluster results for age so this interpretation may make sense, but we’d like more clarity. Thank you for your help.
Freesurfer mailing listFreesurfer@nmr.mgh.harvard.eduhttps://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://secure-web.cisco.com/1WeGUpbfdqUWSods4JqJRgXqQxv5cjYcbDLSvE5VMK-BO83... 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 Mass General Brigham Compliance HelpLine at http://secure-web.cisco.com/187ps7Rfm-qKpuzmaylI7t8yekHGADbfBSjAZfdoFmeTSsdn... . 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. Please note that this e-mail is not secure (encrypted). If you do not wish to continue communication over unencrypted e-mail, please notify the sender of this message immediately. Continuing to send or respond to e-mail after receiving this message means you understand and accept this risk and wish to continue to communicate over unencrypted e-mail.
Assuming you used y = pre-post, then the correlation is the correlation between y and age, so if it is positive it means that the pre-post difference is increasing with age
On 12/16/2021 2:45 PM, PDMD SRALab wrote:
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We are using the paired analysis approach as outlined here (*MailScanner has detected a possible fraud attempt from "secure-web.cisco.com" claiming to be* https://surfer.nmr.mgh.harvard.edu/fswiki/PairedAnalysis https://secure-web.cisco.com/13QTl-VyyAVXvg-0pygxBoVuOM74Yxhp2T1X_88Q9Q9Lh3ZcBaZjKeNXs8tO5B1CS4fZtvL61gNWMgdPO9MHB-7POi_LxXSWFzwW6PtmuEw4Guc640z00rTXgigZmocb05oKYXRzVyV2jqBD-8cyE_B7Z6jdYzIaLDICEgJbuKAhw78DX5l8Tj0Hb48p-ESRe9-FJFvp-SpJQzgKIOlAtppYluJ1RUmyGkhpNiaqgeVFSxd3Azo3E6z7ez5pANkWBsq_9iUepqDNSiuaFacX3p1cERenP__b7wqvD4a5afWTq6s743Bk_a7RuOcX9hmUY/https%3A%2F%2Fsurfer.nmr.mgh.harvard.edu%2Ffswiki%2FPairedAnalysis) so yes we are subtracting the two time points explicitly and computing a paired t-test as you suggested. I've attached both the first fsgd file (pairs.fsgd) and the second fsgd file (paired-diff.fsgd) for your reference. Thanks for the help! - Doug M
On Fri, Dec 10, 2021 at 5:49 PM Douglas N. Greve dgreve@mgh.harvard.edu wrote:
Can you say more about your approach? Are you subtracting the two time points explicitly and computing a paired t? Or are you using the repeated measures anova approach. Send the FSGD file On 11/30/2021 11:04 AM, PDMD SRALab wrote:External Email - Use Caution We are using a paired analysis approach to study cortical thickness in a dataset with 2 timepoints (called pre-protocol and post-protocol). Regarding the mean cluster summary (contrast: [1 0]), we understand positive values to mean pre > post (thinning) and negative values to mean post > pre (thickening). The covariate results are more difficult to interpret. For instance, we’re interested in looking at the effects of age (contrast: [0 1]) on the cortical thickness results. In the age cluster summary, is it fair to interpret positive results as positive correlation (older subjects show more thickening) and negative results as inverse correlation (older subjects show more thinning) or is the interpretation more complex than this? We’re getting mainly negative cluster results for age so this interpretation may make sense, but we’d like more clarity. Thank you for your help. _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu *MailScanner has detected a possible fraud attempt from "secure-web.cisco.com" claiming to be* https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer <https://secure-web.cisco.com/1WeGUpbfdqUWSods4JqJRgXqQxv5cjYcbDLSvE5VMK-BO83L2caX5gjMrZfRhDKz-bbL-IUM1TOExtas1MEe_eZ89v-PD_VT2MHnvLRuLF3UG1DpCQU1DdJlxOTBnZMAh1nKdnPy17_dXUWdvpIsdcwXqa9fSSd93PWdlYRhLH1QepwxXsNTPDGnrDLXlDmb2kT9j4VUqzMbm5o0XpOcLYFk2yA6GF3Bi4r7NBBj97SgvNbFYuaNgsIeV42Z1gRXUd3AGeXudSv078eNIAOT8of8kL7Etrn8hdzC_3afFMmpcSbYXXI_p9-WZmz3-jguL/https%3A%2F%2Fmail.nmr.mgh.harvard.edu%2Fmailman%2Flistinfo%2Ffreesurfer>_______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu *MailScanner has detected a possible fraud attempt from "secure-web.cisco.com" claiming to be* https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer <https://secure-web.cisco.com/1WeGUpbfdqUWSods4JqJRgXqQxv5cjYcbDLSvE5VMK-BO83L2caX5gjMrZfRhDKz-bbL-IUM1TOExtas1MEe_eZ89v-PD_VT2MHnvLRuLF3UG1DpCQU1DdJlxOTBnZMAh1nKdnPy17_dXUWdvpIsdcwXqa9fSSd93PWdlYRhLH1QepwxXsNTPDGnrDLXlDmb2kT9j4VUqzMbm5o0XpOcLYFk2yA6GF3Bi4r7NBBj97SgvNbFYuaNgsIeV42Z1gRXUd3AGeXudSv078eNIAOT8of8kL7Etrn8hdzC_3afFMmpcSbYXXI_p9-WZmz3-jguL/https%3A%2F%2Fmail.nmr.mgh.harvard.edu%2Fmailman%2Flistinfo%2Ffreesurfer> 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 Mass General Brigham Compliance HelpLine at *MailScanner has detected a possible fraud attempt from "secure-web.cisco.com" claiming to be* http://www.massgeneralbrigham.org/complianceline <http://secure-web.cisco.com/187ps7Rfm-qKpuzmaylI7t8yekHGADbfBSjAZfdoFmeTSsdn1ilcbOIf9LIktcA1N0EodcwswEd9R5MLXYr7bwGtSgmzUbSpnXFi_SJjXh0Vh7D9GLIG5kQb_CqkOtb-_0KmZFEvstWK59RxEnPsfHK6Yyhpzq3JltufMDkC_w-XcOjPbGwKIPbqw6a2BsHtJ9F5iz6faKS89PjvzPzakF8jZcOOWPMKHraqwrhfk4C_tNSNZCArBHf1n9rBHx2YFRY8gmbh-IOkTKjqCliMw6KNfn_g4A0LK95UF0a8EJ--WVCeAT2FpvGCZOyGyPON3/http%3A%2F%2Fwww.massgeneralbrigham.org%2Fcomplianceline> . 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. Please note that this e-mail is not secure (encrypted). If you do not wish to continue communication over unencrypted e-mail, please notify the sender of this message immediately. Continuing to send or respond to e-mail after receiving this message means you understand and accept this risk and wish to continue to communicate over unencrypted e-mail.
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Douglas N. Greve -
PDMD SRALab