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

Help for SPM Archives


SPM Archives

SPM Archives


SPM@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

SPM Home

SPM Home

SPM  July 2009

SPM July 2009

Options

Subscribe or Unsubscribe

Subscribe or Unsubscribe

Log In

Log In

Get Password

Get Password

Subject:

Re: t-to-p conversion with spm_imcalc_ui

From:

DRC SPM <[log in to unmask]>

Reply-To:

DRC SPM <[log in to unmask]>

Date:

Mon, 27 Jul 2009 09:20:08 +0100

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (38 lines)

Hi Yaman Aksu,

The interpolation only has any effect if you have multiple images
which are not resampled to have matching voxels (but are aligned in
mm-space via their headers). With one image, I think you should get
identical results with hold=0 and hold=1, as both will essentially
just sample at integer voxel coordinate locations.

Last time I looked, there was no way to automate the p-value image
creation in SPM. I think the reason for this is that it's not so easy
to get an FWE corrected p-value image -- if I remember correctly,
something breaks somewhere for low (insignificant) t-values, in that
instead of p near 1, you get NaN. It would be possible though, as
SurfStat essentially allows this, see SurfStatP,
  http://www.stat.uchicago.edu/~worsley/surfstat/

Best,
Ged

2009/7/25 Yaman Aksu <[log in to unmask]>:
> A previously posted script (cg_t2x.m) converts the t-stat (spmT_...) image to a p-value
> image this way:
>    spm_imcalc_ui(t_file,p_file,['1-spm_Tcdf(i1,' num2str(df) ')'],{0 0 4 1});
> I changed the 4 to 16 to save as 32-bit float. Then I wanted to switch interpolation off, as I
> believe this particular image conversion does not need to involve resampling. Upon reading
> the help pages for the 'interpolation hold' option (incl. the central 'help spm_slice_volume'),
> seems unclear how to switch interpolation off. Especially if you're familiar cg_t2x.m, could
> you help clarify command usage for spm_imcalc_ui for the t-to-p image conversion? Not
> being the author of the above code line, I obviously don't/can't know why the 'interpolation
> hold' has been changed above to 1 (trilinear) from its default value 0 (nearest neighbor).
> Lastly, on a related note, I invoke
>    spm_contrasts(SPM);
> to create the spmT_... image, so, if possible to tell spm_contrasts (by setting a flag inside
> the 'SPM' object) to additionally create the p-value image then please let me know as I'd
> prefer that approach to the spm_imcalc_ui approach above.
> Thank you.
>

Top of Message | Previous Page | Permalink

JiscMail Tools


RSS Feeds and Sharing


Advanced Options


Archives

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
2000
1999
1998


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