Dear Freesurfers,
I am studying cortical thickness as a function of age (continuous) and meditation practice (categorical, level1=Normal, level2=TM). I have three separate cases of qdec, regression1, regression2 and regression3.
Regression1: Discrete (Fixed Factor) = meditation; Continuous (Covariate) = age Regression2: Discrete (Fixed Factor) = meditation; Regression3: Discrete (Fixed Factor) = meditation; Nuisance Factor = age
For the question "Does the average thickness differ between Normal and TM?", Regression1 and Regression3 have identical result, which is different from Regression2, i.e., (1 = 3 !=2 ). May I infer from this result the following about qdec:
1) Regression1 and Regression3 both fit cortical thickness,y, to the model y = b0 + age*b1 + meditation*b2 + err = y_hat + err Regression2 fits: y = b0 + b2*meditation + err = y_hat + err
2) Some function of y_hat goes into the "average thickness", hence the difference between 2 and the others.
However, what role does "Nuisance Factor" play in this case?
Thank you very much!
Sincerely, Ye
1 and 3 are the same model. Calling a variable a nuisance factor is just a description. The model is actually y = age*meditation*b1 + meditation*b2 + err = y_hat + err
doug
On 8/13/13 6:12 PM, ye tian wrote:
Dear Freesurfers,
I am studying cortical thickness as a function of age (continuous) and meditation practice (categorical, level1=Normal, level2=TM). I have three separate cases of qdec, regression1, regression2 and regression3.
Regression1: Discrete (Fixed Factor) = meditation; Continuous (Covariate) = age Regression2: Discrete (Fixed Factor) = meditation; Regression3: Discrete (Fixed Factor) = meditation; Nuisance Factor = age
For the question "Does the average thickness differ between Normal and TM?", Regression1 and Regression3 have identical result, which is different from Regression2, i.e., (1 = 3 !=2 ). May I infer from this result the following about qdec:
Regression1 and Regression3 both fit cortical thickness,y, to the model y = b0 + age*b1 + meditation*b2 + err = y_hat + err Regression2 fits: y = b0 + b2*meditation + err = y_hat + err
Some function of y_hat goes into the "average thickness", hence
the difference between 2 and the others.
However, what role does "Nuisance Factor" play in this case?
Thank you very much!
Sincerely, Ye
Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
Dear Doug,
Would you please shine some light on what quantities are being plotted in those statistical maps of QDEC? Some linear combination of the columns of the design matrix?
Also, what is the "default" design matrix?
Thank you very much!
Sincerely, Ye
On Tue, Aug 13, 2013 at 11:45 PM, Douglas Greve greve@nmr.mgh.harvard.eduwrote:
1 and 3 are the same model. Calling a variable a nuisance factor is just a description. The model is actually y = age*meditation*b1 + meditation*b2 + err = y_hat + err
doug
On 8/13/13 6:12 PM, ye tian wrote:
Dear Freesurfers,
I am studying cortical thickness as a function of age (continuous) and meditation practice (categorical, level1=Normal, level2=TM). I have three separate cases of qdec, regression1, regression2 and regression3.
Regression1: Discrete (Fixed Factor) = meditation; Continuous (Covariate) = age Regression2: Discrete (Fixed Factor) = meditation; Regression3: Discrete (Fixed Factor) = meditation; Nuisance Factor = age
For the question "Does the average thickness differ between Normal and TM?", Regression1 and Regression3 have identical result, which is different from Regression2, i.e., (1 = 3 !=2 ). May I infer from this result the following about qdec:
- Regression1 and Regression3 both fit cortical thickness,y, to the
model y = b0 + age*b1 + meditation*b2 + err = y_hat + err Regression2 fits: y = b0 + b2*meditation + err = y_hat + err
- Some function of y_hat goes into the "average thickness", hence the
difference between 2 and the others.
However, what role does "Nuisance Factor" play in this case?
Thank you very much!
Sincerely, Ye
Freesurfer mailing listFreesurfer@nmr.mgh.harvard.eduhttps://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
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.
-log10(p) which p is the pvalue for the statistical test. The color is signed by the test.
On 08/19/2013 11:19 AM, ye tian wrote:
Dear Doug,
Would you please shine some light on what quantities are being plotted in those statistical maps of QDEC? Some linear combination of the columns of the design matrix?
Also, what is the "default" design matrix?
Thank you very much!
Sincerely, Ye
On Tue, Aug 13, 2013 at 11:45 PM, Douglas Greve <greve@nmr.mgh.harvard.edu mailto:greve@nmr.mgh.harvard.edu> wrote:
1 and 3 are the same model. Calling a variable a nuisance factor is just a description. The model is actually y = age*meditation*b1 + meditation*b2 + err = y_hat + err doug On 8/13/13 6:12 PM, ye tian wrote:Dear Freesurfers, I am studying cortical thickness as a function of age (continuous) and meditation practice (categorical, level1=Normal, level2=TM). I have three separate cases of qdec, regression1, regression2 and regression3. Regression1: Discrete (Fixed Factor) = meditation; Continuous (Covariate) = age Regression2: Discrete (Fixed Factor) = meditation; Regression3: Discrete (Fixed Factor) = meditation; Nuisance Factor = age For the question "Does the average thickness differ between Normal and TM?", Regression1 and Regression3 have identical result, which is different from Regression2, i.e., (1 = 3 !=2 ). May I infer from this result the following about qdec: 1) Regression1 and Regression3 both fit cortical thickness,y, to the model y = b0 + age*b1 + meditation*b2 + err = y_hat + err Regression2 fits: y = b0 + b2*meditation + err = y_hat + err 2) Some function of y_hat goes into the "average thickness", hence the difference between 2 and the others. However, what role does "Nuisance Factor" play in this case? Thank you very much! Sincerely, Ye _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer_______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto: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.
Dear Doug,
If I only have two groups, does the statistical test reduce to a two-tail t-test?
Sorry, I meant to ask what the "default" contrast is, meaning what the contrast is when I specify no nuisance factor?
Is there an official document where the QDEC setup is gone over systematically?
Thank you very much!
Sincerely, Ye
On Mon, Aug 19, 2013 at 11:04 AM, Douglas N Greve <greve@nmr.mgh.harvard.edu
wrote:
-log10(p) which p is the pvalue for the statistical test. The color is signed by the test.
On 08/19/2013 11:19 AM, ye tian wrote:
Dear Doug,
Would you please shine some light on what quantities are being plotted in those statistical maps of QDEC? Some linear combination of the columns of the design matrix?
Also, what is the "default" design matrix?
Thank you very much!
Sincerely, Ye
On Tue, Aug 13, 2013 at 11:45 PM, Douglas Greve < greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.**edugreve@nmr.mgh.harvard.edu>> wrote:
1 and 3 are the same model. Calling a variable a nuisance factor is just a description. The model is actually y = age*meditation*b1 + meditation*b2 + err = y_hat + err doug On 8/13/13 6:12 PM, ye tian wrote:Dear Freesurfers, I am studying cortical thickness as a function of age (continuous) and meditation practice (categorical, level1=Normal, level2=TM). I have three separate cases of qdec, regression1, regression2 and regression3. Regression1: Discrete (Fixed Factor) = meditation; Continuous (Covariate) = age Regression2: Discrete (Fixed Factor) = meditation; Regression3: Discrete (Fixed Factor) = meditation; Nuisance Factor = age For the question "Does the average thickness differ between Normal and TM?", Regression1 and Regression3 have identical result, which is different from Regression2, i.e., (1 = 3 !=2 ). May I infer from this result the following about qdec: 1) Regression1 and Regression3 both fit cortical thickness,y, to the model y = b0 + age*b1 + meditation*b2 + err = y_hat + err Regression2 fits: y = b0 + b2*meditation + err = y_hat + err 2) Some function of y_hat goes into the "average thickness", hence the difference between 2 and the others. However, what role does "Nuisance Factor" play in this case? Thank you very much! Sincerely, Ye ______________________________**_________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.**harvard.edu Freesurfer@nmr.mgh.harvard.edu> https://mail.nmr.mgh.harvard.**edu/mailman/listinfo/**freesurferhttps://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
______________________________**_________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.**harvard.edu Freesurfer@nmr.mgh.harvard.edu>
https://mail.nmr.mgh.harvard.**edu/mailman/listinfo/**freesurfer<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<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.-- 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/BugReportinghttp://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.**edu/filedrop2https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/**facility/filedrop/index.htmlhttp://www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.**edu/transfer/outgoing/flat/** greve/ ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/
QDEC creates a sentence that describes each contrast. Is that sentence not clear? I think the only other docs we have for QDEC are the tutorial. doug
On 08/19/2013 12:19 PM, ye tian wrote:
Dear Doug,
If I only have two groups, does the statistical test reduce to a two-tail t-test?
Sorry, I meant to ask what the "default" contrast is, meaning what the contrast is when I specify no nuisance factor?
Is there an official document where the QDEC setup is gone over systematically?
Thank you very much!
Sincerely, Ye
On Mon, Aug 19, 2013 at 11:04 AM, Douglas N Greve <greve@nmr.mgh.harvard.edu mailto:greve@nmr.mgh.harvard.edu> wrote:
-log10(p) which p is the pvalue for the statistical test. The color is signed by the test. On 08/19/2013 11:19 AM, ye tian wrote: Dear Doug, Would you please shine some light on what quantities are being plotted in those statistical maps of QDEC? Some linear combination of the columns of the design matrix? Also, what is the "default" design matrix? Thank you very much! Sincerely, Ye On Tue, Aug 13, 2013 at 11:45 PM, Douglas Greve <greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu> <mailto:greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>>> wrote: 1 and 3 are the same model. Calling a variable a nuisance factor is just a description. The model is actually y = age*meditation*b1 + meditation*b2 + err = y_hat + err doug On 8/13/13 6:12 PM, ye tian wrote: Dear Freesurfers, I am studying cortical thickness as a function of age (continuous) and meditation practice (categorical, level1=Normal, level2=TM). I have three separate cases of qdec, regression1, regression2 and regression3. Regression1: Discrete (Fixed Factor) = meditation; Continuous (Covariate) = age Regression2: Discrete (Fixed Factor) = meditation; Regression3: Discrete (Fixed Factor) = meditation; Nuisance Factor = age For the question "Does the average thickness differ between Normal and TM?", Regression1 and Regression3 have identical result, which is different from Regression2, i.e., (1 = 3 !=2 ). May I infer from this result the following about qdec: 1) Regression1 and Regression3 both fit cortical thickness,y, to the model y = b0 + age*b1 + meditation*b2 + err = y_hat + err Regression2 fits: y = b0 + b2*meditation + err = y_hat + err 2) Some function of y_hat goes into the "average thickness", hence the difference between 2 and the others. However, what role does "Nuisance Factor" play in this case? Thank you very much! Sincerely, Ye _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu>> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.harvard.edu <mailto: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. -- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu> Phone Number: 617-724-2358 <tel:617-724-2358> Fax: 617-726-7422 <tel:617-726-7422> Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting <http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting> FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html <http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html> Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/
Dear Doug,
Would you please let me know what the general formula for the model is for discrete variables x1, x2, .... , xN, covarying with continuous variables z1, z2, ..., zM? Is it
y = error + bi*xi + cij*xi*zj ?
Otherwise, how does freesurfer decide what model to use?
Thank you very much!
Sincerely, Ye
On Mon, Aug 19, 2013 at 11:26 AM, Douglas N Greve <greve@nmr.mgh.harvard.edu
wrote:
QDEC creates a sentence that describes each contrast. Is that sentence not clear? I think the only other docs we have for QDEC are the tutorial. doug
On 08/19/2013 12:19 PM, ye tian wrote:
Dear Doug,
If I only have two groups, does the statistical test reduce to a two-tail t-test?
Sorry, I meant to ask what the "default" contrast is, meaning what the contrast is when I specify no nuisance factor?
Is there an official document where the QDEC setup is gone over systematically?
Thank you very much!
Sincerely, Ye
On Mon, Aug 19, 2013 at 11:04 AM, Douglas N Greve < greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.**edugreve@nmr.mgh.harvard.edu>> wrote:
-log10(p) which p is the pvalue for the statistical test. The color is signed by the test. On 08/19/2013 11:19 AM, ye tian wrote: Dear Doug, Would you please shine some light on what quantities are being plotted in those statistical maps of QDEC? Some linear combination of the columns of the design matrix? Also, what is the "default" design matrix? Thank you very much! Sincerely, Ye On Tue, Aug 13, 2013 at 11:45 PM, Douglas Greve <greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.**edu<greve@nmr.mgh.harvard.edu><mailto:greve@nmr.mgh.harvard.**edu <greve@nmr.mgh.harvard.edu> <mailto:greve@nmr.mgh.harvard.**edu <greve@nmr.mgh.harvard.edu>>>>wrote:
1 and 3 are the same model. Calling a variable a nuisance factor is just a description. The model is actually y = age*meditation*b1 + meditation*b2 + err = y_hat + err doug On 8/13/13 6:12 PM, ye tian wrote: Dear Freesurfers, I am studying cortical thickness as a function of age (continuous) and meditation practice (categorical, level1=Normal, level2=TM). I have three separate cases of qdec, regression1, regression2 and regression3. Regression1: Discrete (Fixed Factor) = meditation; Continuous (Covariate) = age Regression2: Discrete (Fixed Factor) = meditation; Regression3: Discrete (Fixed Factor) = meditation; Nuisance Factor = age For the question "Does the average thickness differ between Normal and TM?", Regression1 and Regression3 have identical result, which is different from Regression2, i.e., (1 = 3 !=2 ). May I infer from this result the following about qdec: 1) Regression1 and Regression3 both fit cortical thickness,y, to the model y = b0 + age*b1 + meditation*b2 + err = y_hat + err Regression2 fits: y = b0 + b2*meditation + err = y_hat + err 2) Some function of y_hat goes into the "average thickness", hence the difference between 2 and the others. However, what role does "Nuisance Factor" play in this case? Thank you very much! Sincerely, Ye ______________________________**_________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu><mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu>https://mail.nmr.mgh.harvard.**edu/mailman/listinfo/**freesurfer https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
______________________________**_________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu><mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu>https://mail.nmr.mgh.harvard.**edu/mailman/listinfo/**freesurfer<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<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. -- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.**edu<greve@nmr.mgh.harvard.edu>Phone Number: 617-724-2358 <tel:617-724-2358> Fax: 617-726-7422 <tel:617-726-7422> Bugs: surfer.nmr.mgh.harvard.edu/**fswiki/BugReporting<http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting> <http://surfer.nmr.mgh.**harvard.edu/fswiki/**BugReporting<http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting>FileDrop: https://gate.nmr.mgh.harvard.**edu/filedrop2<https://gate.nmr.mgh.harvard.edu/filedrop2> www.nmr.mgh.harvard.edu/**facility/filedrop/index.html<http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html> <http://www.nmr.mgh.harvard.**edu/facility/filedrop/index.**html<http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html>Outgoing: ftp://surfer.nmr.mgh.harvard.**edu/transfer/outgoing/flat/**greve/<ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/>-- 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/BugReportinghttp://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.**edu/filedrop2https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/**facility/filedrop/index.htmlhttp://www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.**edu/transfer/outgoing/flat/** greve/ ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/
Yes, that is correct for DODS. For DOSS, it is y = e + bi*xi + ci*zi doug
On 09/03/2013 01:03 PM, ye tian wrote:
Dear Doug,
Would you please let me know what the general formula for the model is for discrete variables x1, x2, .... , xN, covarying with continuous variables z1, z2, ..., zM? Is it
y = error + bi*xi + cij*xi*zj ?
Otherwise, how does freesurfer decide what model to use?
Thank you very much!
Sincerely, Ye
On Mon, Aug 19, 2013 at 11:26 AM, Douglas N Greve <greve@nmr.mgh.harvard.edu mailto:greve@nmr.mgh.harvard.edu> wrote:
QDEC creates a sentence that describes each contrast. Is that sentence not clear? I think the only other docs we have for QDEC are the tutorial. doug On 08/19/2013 12:19 PM, ye tian wrote: Dear Doug, If I only have two groups, does the statistical test reduce to a two-tail t-test? Sorry, I meant to ask what the "default" contrast is, meaning what the contrast is when I specify no nuisance factor? Is there an official document where the QDEC setup is gone over systematically? Thank you very much! Sincerely, Ye On Mon, Aug 19, 2013 at 11:04 AM, Douglas N Greve <greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu> <mailto:greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>>> wrote: -log10(p) which p is the pvalue for the statistical test. The color is signed by the test. On 08/19/2013 11:19 AM, ye tian wrote: Dear Doug, Would you please shine some light on what quantities are being plotted in those statistical maps of QDEC? Some linear combination of the columns of the design matrix? Also, what is the "default" design matrix? Thank you very much! Sincerely, Ye On Tue, Aug 13, 2013 at 11:45 PM, Douglas Greve <greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu> <mailto:greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>> <mailto:greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu> <mailto:greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>>>> wrote: 1 and 3 are the same model. Calling a variable a nuisance factor is just a description. The model is actually y = age*meditation*b1 + meditation*b2 + err = y_hat + err doug On 8/13/13 6:12 PM, ye tian wrote: Dear Freesurfers, I am studying cortical thickness as a function of age (continuous) and meditation practice (categorical, level1=Normal, level2=TM). I have three separate cases of qdec, regression1, regression2 and regression3. Regression1: Discrete (Fixed Factor) = meditation; Continuous (Covariate) = age Regression2: Discrete (Fixed Factor) = meditation; Regression3: Discrete (Fixed Factor) = meditation; Nuisance Factor = age For the question "Does the average thickness differ between Normal and TM?", Regression1 and Regression3 have identical result, which is different from Regression2, i.e., (1 = 3 !=2 ). May I infer from this result the following about qdec: 1) Regression1 and Regression3 both fit cortical thickness,y, to the model y = b0 + age*b1 + meditation*b2 + err = y_hat + err Regression2 fits: y = b0 + b2*meditation + err = y_hat + err 2) Some function of y_hat goes into the "average thickness", hence the difference between 2 and the others. However, what role does "Nuisance Factor" play in this case? Thank you very much! Sincerely, Ye _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu>> <mailto:Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu>>> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu>> <mailto:Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.harvard.edu <mailto: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. -- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu> <mailto:greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu>> Phone Number: 617-724-2358 <tel:617-724-2358> <tel:617-724-2358 <tel:617-724-2358>> Fax: 617-726-7422 <tel:617-726-7422> <tel:617-726-7422 <tel:617-726-7422>> Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting <http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting> <http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting> FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html <http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html> <http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html> Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ -- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu> Phone Number: 617-724-2358 <tel:617-724-2358> Fax: 617-726-7422 <tel:617-726-7422> Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting <http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting> FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html <http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html> Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/
Dear Doug,
Thank you very much!
Sincerely, Ye
On Tue, Sep 3, 2013 at 5:29 PM, Douglas N Greve greve@nmr.mgh.harvard.eduwrote:
Yes, that is correct for DODS. For DOSS, it is y = e + bi*xi + ci*zi doug
On 09/03/2013 01:03 PM, ye tian wrote:
Dear Doug,
Would you please let me know what the general formula for the model is for discrete variables x1, x2, .... , xN, covarying with continuous variables z1, z2, ..., zM? Is it
y = error + bi*xi + cij*xi*zj ?
Otherwise, how does freesurfer decide what model to use?
Thank you very much!
Sincerely, Ye
On Mon, Aug 19, 2013 at 11:26 AM, Douglas N Greve < greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.**edugreve@nmr.mgh.harvard.edu>> wrote:
QDEC creates a sentence that describes each contrast. Is that sentence not clear? I think the only other docs we have for QDEC are the tutorial. doug On 08/19/2013 12:19 PM, ye tian wrote: Dear Doug, If I only have two groups, does the statistical test reduce to a two-tail t-test? Sorry, I meant to ask what the "default" contrast is, meaning what the contrast is when I specify no nuisance factor? Is there an official document where the QDEC setup is gone over systematically? Thank you very much! Sincerely, Ye On Mon, Aug 19, 2013 at 11:04 AM, Douglas N Greve <greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.**edu<greve@nmr.mgh.harvard.edu><mailto:greve@nmr.mgh.harvard.**edu <greve@nmr.mgh.harvard.edu> <mailto:greve@nmr.mgh.harvard.**edu <greve@nmr.mgh.harvard.edu>>>>wrote:
-log10(p) which p is the pvalue for the statistical test. The color is signed by the test. On 08/19/2013 11:19 AM, ye tian wrote: Dear Doug, Would you please shine some light on what quantities are being plotted in those statistical maps of QDEC? Some linear combination of the columns of the design matrix? Also, what is the "default" design matrix? Thank you very much! Sincerely, Ye On Tue, Aug 13, 2013 at 11:45 PM, Douglas Greve <greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.**edu <greve@nmr.mgh.harvard.edu>> <mailto:greve@nmr.mgh.harvard.**edu <greve@nmr.mgh.harvard.edu> <mailto:greve@nmr.mgh.harvard.**edu <greve@nmr.mgh.harvard.edu>>> <mailto:greve@nmr.mgh.harvard.**edu<greve@nmr.mgh.harvard.edu> <mailto:greve@nmr.mgh.harvard.**edu <greve@nmr.mgh.harvard.edu>> <mailto:greve@nmr.mgh.harvard.**edu<greve@nmr.mgh.harvard.edu> <mailto:greve@nmr.mgh.harvard.**edu <greve@nmr.mgh.harvard.edu>>>>>wrote:
1 and 3 are the same model. Calling a variable a nuisance factor is just a description. The model is actually y = age*meditation*b1 + meditation*b2 + err = y_hat + err doug On 8/13/13 6:12 PM, ye tian wrote: Dear Freesurfers, I am studying cortical thickness as a function of age (continuous) and meditation practice (categorical, level1=Normal, level2=TM). I have three separate cases of qdec, regression1, regression2 and regression3. Regression1: Discrete (Fixed Factor) = meditation; Continuous (Covariate) = age Regression2: Discrete (Fixed Factor) = meditation; Regression3: Discrete (Fixed Factor) = meditation; Nuisance Factor = age For the question "Does the average thickness differ between Normal and TM?", Regression1 and Regression3 have identical result, which is different from Regression2, i.e., (1 = 3 !=2 ). May I infer from this result the following about qdec: 1) Regression1 and Regression3 both fit cortical thickness,y, to the model y = b0 + age*b1 + meditation*b2 + err = y_hat + err Regression2 fits: y = b0 + b2*meditation + err = y_hat + err 2) Some function of y_hat goes into the "average thickness", hence the difference between 2 and the others. However, what role does "Nuisance Factor" play in this case? Thank you very much! Sincerely, Ye ______________________________**_________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu><mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu><mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu><mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu>https://mail.nmr.mgh.harvard.**edu/mailman/listinfo/**freesurfer<https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer> ______________________________**_________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu><mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu><mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu><mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu> <mailto:Freesurfer@nmr.mgh.**harvard.edu<Freesurfer@nmr.mgh.harvard.edu>https://mail.nmr.mgh.harvard.**edu/mailman/listinfo/**freesurfer<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<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. -- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.**edu<greve@nmr.mgh.harvard.edu><mailto:greve@nmr.mgh.harvard.**edu <greve@nmr.mgh.harvard.edu> <mailto:greve@nmr.mgh.harvard.**edu <greve@nmr.mgh.harvard.edu>>> Phone Number: 617-724-2358 <tel:617-724-2358> <tel:617-724-2358 <tel:617-724-2358>> Fax: 617-726-7422 <tel:617-726-7422> <tel:617-726-7422 <tel:617-726-7422>> Bugs: surfer.nmr.mgh.harvard.edu/**fswiki/BugReporting<http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting> <http://surfer.nmr.mgh.**harvard.edu/fswiki/**BugReporting<http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting><http://surfer.nmr.mgh.**harvard.edu/fswiki/**BugReporting<http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting>FileDrop: https://gate.nmr.mgh.harvard.**edu/filedrop2<https://gate.nmr.mgh.harvard.edu/filedrop2> www.nmr.mgh.harvard.edu/**facility/filedrop/index.html<http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html> <http://www.nmr.mgh.harvard.**edu/facility/filedrop/index.**html<http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html><http://www.nmr.mgh.harvard.**edu/facility/filedrop/index.**html http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html> Outgoing: ftp://surfer.nmr.mgh.harvard.**edu/transfer/outgoing/flat/** greve/ ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/
-- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.**edu<greve@nmr.mgh.harvard.edu>Phone Number: 617-724-2358 <tel:617-724-2358> Fax: 617-726-7422 <tel:617-726-7422> Bugs: surfer.nmr.mgh.harvard.edu/**fswiki/BugReporting<http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting> <http://surfer.nmr.mgh.**harvard.edu/fswiki/**BugReporting<http://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting>FileDrop: https://gate.nmr.mgh.harvard.**edu/filedrop2<https://gate.nmr.mgh.harvard.edu/filedrop2> www.nmr.mgh.harvard.edu/**facility/filedrop/index.html<http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html> <http://www.nmr.mgh.harvard.**edu/facility/filedrop/index.**html<http://www.nmr.mgh.harvard.edu/facility/filedrop/index.html>Outgoing: ftp://surfer.nmr.mgh.harvard.**edu/transfer/outgoing/flat/**greve/<ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/>-- 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/BugReportinghttp://surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.**edu/filedrop2https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/**facility/filedrop/index.htmlhttp://www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.**edu/transfer/outgoing/flat/** greve/ ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/
freesurfer@nmr.mgh.harvard.edu
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Douglas Greve -
Douglas N Greve
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ye tian