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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Hi Jan-Mathijs,
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<div>Thanks for this response.</div>
<div>I still have a question though.</div>
<div>You mentioned that it is not necessary to use ft_sourcegrandaverage to perform statistical analysis with source space ERFs across multiple participants. However, what you appeared to suggest in your email, does appear to still use a grand average, e.g.
you wrote:</div>
<div><br>
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<div>
<div style="font-family: 'Times New Roman';"><font size="2">>you can do something like this</font></div>
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</font></div>
<div style="font-family: 'Times New Roman';"><font size="2">>cfg = your cfg to ft_sourcestatistics</font></div>
<div style="font-family: 'Times New Roman';"><font size="2">>stat = ft_sourcestatistics(cfg,
<font color="#ff0000">grandavg</font>{:});</font></div>
</div>
<div><br>
</div>
<div>Having played around with it a bit more, I am still unclear how to use multiple inputs (e.g., multiple subjects source data) when using ft_sourcestatistics. I had thought that ft_sourcegrandavarge was a necessity. </div>
<div>Can you make this a bit clearer?</div>
<div><br>
</div>
<div>Also, I did go back and use cfg.fixedori='yes' when calling my first ft_srouceanalysis and moved also my source.avg.mom data into source.avg.pow as you suggested, but this still leaves me with the question above- how to use multiple subjects source data
in <span style="font-size: 10pt;">ft_sourcestatistics?</span></div>
<div><span style="font-size: 10pt;"><br>
</span></div>
<div><span style="font-size: 10pt;">Once again, any help from anyone would be much </span>appreciated!</div>
<div><br>
</div>
<div>Kaelasha</div>
<div><br>
<div style="font-family: Times New Roman; color: #000000; font-size: 16px">
<hr tabindex="-1">
<div id="divRpF615831" style="direction: ltr;"><font face="Tahoma" size="2" color="#000000"><b>From:</b> fieldtrip-bounces@science.ru.nl [fieldtrip-bounces@science.ru.nl] on behalf of jan-mathijs schoffelen [jan.schoffelen@donders.ru.nl]<br>
<b>Sent:</b> Tuesday, 14 January 2014 5:52 PM<br>
<b>To:</b> FieldTrip discussion list<br>
<b>Subject:</b> Re: [FieldTrip] ft_sourcestatistics and sourcegrandaverage time series<br>
</font><br>
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<div></div>
<div>Hi Kaelasha,
<div><br>
</div>
<div>You actually don't need to use ft_sourcegrandaverage if your goal is to do statistics. Ft_sourcestatistics in principle knows how to deal with multiple inputs.</div>
<div>Thus,</div>
<div>rather than doing</div>
<div><br>
</div>
<div>cfg = [];</div>
<div>cfg.keepindividual = 'yes';</div>
<div>grandavg = ft_sourcegrandaverage(cfg, subjectdata{:});</div>
<div><br>
</div>
<div>you can do something like this</div>
<div><br>
</div>
<div>cfg = your cfg to ft_sourcestatistics</div>
<div>stat = ft_sourcestatistics(cfg, grandavg{:});</div>
<div><br>
</div>
<div>Now, the question boils down to 'how to fool ft_sourcestatistics to swallow my data?'.</div>
<div><br>
</div>
<div>The following should more or less work (but requires some manual labour):</div>
<div><br>
</div>
<div>The time courses at the voxel level are present in source.avg.mom. These are most likely 3xN, 3 dipole orientations times N time points. In order to reduce this, one can project the orientation along the first pca-axis. This can be achieved by a call to
ft_sourcedescriptives with cfg.projectmom='yes', or by calling ft_sourceanalysis in the first place with cfg.fixedori = 'yes'. </div>
<div>Then, you could do something like:</div>
<div><br>
</div>
<div>pow = zeros(size(source.pos,1),length(source.time);</div>
<div>pow(source.inside,:) = cat(1,source.avg.mom{source.inside});</div>
<div>source.avg.pow = pow;</div>
<div><br>
</div>
<div>Just to be sure, add a time-axis to the source structure, i.e. source.time = tlck.time (tlck being the data structure used to create the lcmv-output).</div>
<div><br>
</div>
<div>I think this should bring you close to doing statistics.</div>
<div><br>
</div>
<div>Best,</div>
<div>Jan-Mathijs</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
<div>
<div>On Jan 14, 2014, at 7:19 AM, Kaelasha Tyler wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica;">
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Hi all,
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</div>
<div>Reading through the discussion list, I see others have also had some issues with creating grand averaged source space time series (ERFs) and subsequent statistical analysis, but I can't see any solutions....</div>
<div><br>
</div>
<div>Questions:</div>
<div>How can I create time series (ERFs) for grand averaged source space data?</div>
<div>And, how can I do cluster analysis<span style="font-size:10pt"> on these (yet to be created) grand averaged source space ERFs?</span></div>
<div><br>
</div>
<div><br>
</div>
<div>I have used ft_SOURCEANALYSIS with method 'lcmv' for individual participants to generate source space time series, in data.avg.mom.</div>
<div><br>
</div>
<div>Subsequently I used ft_sourcegrandaverage to combine source space data across subjects. </div>
<div><br>
</div>
<div>However my grand averaged source data.avg only contains 'pow' and no 'mom'. Eg, no time series for the grand averaged source space data. </div>
<div><br>
</div>
<div>As such, I can not do cluster analysis on grand averaged ERFs in source space.</div>
<div><br>
</div>
<div>It appears that ft_sourcestatistics only works with <font size="2">parameters that have not more than one value per </font>grid point<font size="2"> (e.g. pow, nai etc) and is unable to work with ERF time series? Is this true?</font></div>
<div><span style="font-family:Courier; font-size:10px"><br>
</span></div>
<div>Can any one help with this?</div>
<div><br>
</div>
<div>Much obliged.</div>
<div>Kaelasha</div>
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</div>
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</span></div>
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<div>Jan-Mathijs Schoffelen, MD PhD </div>
<div><br>
</div>
<div>Donders Institute for Brain, Cognition and Behaviour, <br>
Centre for Cognitive Neuroimaging,<br>
Radboud University Nijmegen, The Netherlands</div>
<div><br>
</div>
<div>Max Planck Institute for Psycholinguistics,</div>
<div>Nijmegen, The Netherlands</div>
<div><br>
</div>
<div><a href="mailto:J.Schoffelen@donders.ru.nl" target="_blank">J.Schoffelen@donders.ru.nl</a></div>
<div>Telephone: +31-24-3614793</div>
<div><br>
</div>
<div><a href="http://www.hettaligebrein.nl" target="_blank">http://www.hettaligebrein.nl</a></div>
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