JiscMail Logo
Email discussion lists for the UK Education and Research communities

Help for FSL Archives


FSL Archives

FSL Archives


FSL@JISCMAIL.AC.UK


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

FSL Home

FSL Home

FSL  2004

FSL 2004

Options

Subscribe or Unsubscribe

Subscribe or Unsubscribe

Log In

Log In

Get Password

Get Password

Subject:

Re: second level analysis

From:

Tim Behrens <[log in to unmask]>

Reply-To:

FSL - FMRIB's Software Library <[log in to unmask]>

Date:

Wed, 8 Sep 2004 09:17:59 +0100

Content-Type:

TEXT/PLAIN

Parts/Attachments:

Parts/Attachments

TEXT/PLAIN (66 lines)

Hi -
Unfortunately, as you only have two runs per subject, you will not be able
to estimate a between-session variance separately for each subject.

What we advise under these circumstances is to make the assumption that
all subjects in a given group have the same between-session variance.
Then you estimate a single between-session variance for each group, which
will effectively be added onto the variance associated with the
mean of the measurements, and be taken up to the third level.

To do this, you could eaither have 1 big design matrix with 2 groups in
it, or (easier) one design matrix for each group, each of which will look
like:

     GP EV1 EV2 EV3 ....
     1   1   0   0  ....
     1   1   0   0  ....
     1   0   1   0  ....
     1   0   1   0  ....
     1   0   0   1  ....
     1   0   0   1  ....
     .   .   .   .  ....
     .   .   .   .  ....

con:     1   0   0  ....
         0   1   0  ....
         0   0   1  ....


If you take the two DM approach, then you can run the group without your
new subject in, before you collect data from the new subject.

Hope this is useful

T

-------------------------------------------------------------------------------
Tim Behrens
Centre for Functional MRI of the Brain
The John Radcliffe Hospital
Headley Way Oxford OX3 9DU
Oxford University
Work 01865 222782
Mobile 07980 884537
-------------------------------------------------------------------------------

On Tue, 7 Sep 2004, Dost Ongur wrote:

> Hello,
>
> We have a study with 34 subjects in 2 groups (patient and control).  Each
> subject had 2 identical runs.
>
> We are waiting to scan a final patient and have 35 subjects for the
> ultimate analysis.  In the meantime, we would like to go ahead and finish
> the first and second level analyses for all existing data sets.
>
> Is it OK to do the second level analysis (across runs for each subject) for
> the 34 existing subjects in one large batch and then run the final
> subject's data when they become available on its own?  Would we have to
> repeat the second level analysis once we have all 35 scans?
>
> Thanks,
> Dost Ongur
>

Top of Message | Previous Page | Permalink

JiscMail Tools


RSS Feeds and Sharing


Advanced Options


Archives

January 2020
December 2019
November 2019
October 2019
September 2019
August 2019
July 2019
June 2019
May 2019
April 2019
March 2019
February 2019
January 2019
December 2018
November 2018
October 2018
September 2018
August 2018
July 2018
June 2018
May 2018
April 2018
March 2018
February 2018
January 2018
December 2017
November 2017
October 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
November 2016
October 2016
September 2016
August 2016
July 2016
June 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
February 2007
January 2007
2006
2005
2004
2003
2002
2001


JiscMail is a Jisc service.

View our service policies at https://www.jiscmail.ac.uk/policyandsecurity/ and Jisc's privacy policy at https://www.jisc.ac.uk/website/privacy-notice

Secured by F-Secure Anti-Virus CataList Email List Search Powered by the LISTSERV Email List Manager