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<span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400" class="ContentPasted0">Dear Stephan,</span></p>
<p dir="ltr" style="line-height:1.2;margin-top:12pt;margin-bottom:0pt"><span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400" class="ContentPasted0">Thank you for your response, but in this case our
source analysis data does not contain the average across subjects. If you refer to the ‘avg’ structure, it is one of the outputs coming from performing the source analysis by contrasting the pre and post stimulus interval. During the process, I calculate an
inverse filter calculated from both intervals together and then applied separately to each interval, from this process I obtain the output ‘avg’, I do this for each subject and each condition.</span></p>
<p dir="ltr" style="line-height:1.2;margin-top:12pt;margin-bottom:0pt"><span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400" class="ContentPasted0">You can see it in more detail at this link</span><a href="https://www.fieldtriptoolbox.org/tutorial/beamformer/" class="ContentPasted0"><span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400"> </span><span style="font-size:12pt;font-family:'Times New Roman';color:#000080;background-color:#ffffff;font-weight:400;text-decoration:underline;text-decoration-skip-ink:none">https://www.fieldtriptoolbox.org/tutorial/beamformer/</span></a><span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400" class="ContentPasted0"> in
the section </span><span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400;font-style:italic" class="ContentPasted0">‘Source Analysis: Contrasting activity to another interval’.</span></p>
<p dir="ltr" style="line-height:1.2;margin-top:12pt;margin-bottom:0pt"><span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400" class="ContentPasted0">Our source data are distributed as follows, for each
subject I have the mean power of each voxel for each condition independently, perhaps best understood with the following image:</span><a href="https://gyazo.com/00af9e5ca9647bec71d561c4197eefc5" class="ContentPasted0"><span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400"> </span></a><a href="https://gyazo.com/39bb9c919f469d95f984a68b6dca6e18" class="ContentPasted0"><span style="font-size:12pt;font-family:'Times New Roman';color:#1155cc;background-color:#ffffff;font-weight:400;text-decoration:underline;text-decoration-skip-ink:none">https://gyazo.com/39bb9c919f469d95f984a68b6dca6e18</span></a><span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400" class="ContentPasted0"> </span></p>
<br class="ContentPasted0">
<span style="border:none;display:inline-block;overflow:hidden;width:704px;height:348px"><img width="704" height="348" style="margin-top:0px" class="ContentPasted0" src="https://lh6.googleusercontent.com/fLsaCgJYAhYIaQRGNxzNEdwzQN7n10QBbjS-oOeTbhvP68qQ3rBW8dnFa37-Vg2pzaNbY2NiVPCW4YCNLwwed-IpPQfXo-RzL1Sh9ac7LgqEkClX4kIr79C_BAfOvGhmtIMeW-wgY5VYJ31TSbyQpcllTBTnD13S5roabFDKvjtghYDMV7sr-2Kz1Hanbg"></span>
<p dir="ltr" style="line-height:1.3090909090909089;margin-top:0pt;margin-bottom:0pt">
<span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400" class="ContentPasted0">We suspect that the problem could stem from the fact that our data structure differs from the one described in the tutorial
for ft_sourcestatistics in that we do not provide sources from each trail, but the average source of each condition instead. So, our question is whether with this data structure we can perform a nonparametric randomization test, by creating the null hypothesis
distribution shuffling voxels between conditions and then obtain an 'average' null distribution across subjects. I am not sure if this makes sense. Another way could be to shuffle conditions across subjects and obtain a null hypothesis distribution from this
shuffle.</span></p>
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<span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400" class="ContentPasted0">Thank you again,</span></p>
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<span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400" class="ContentPasted0">Best,</span></p>
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<span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400" class="ContentPasted0">Francisco Javier Gómez</span></p>
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<span style="font-size:12pt;font-family:'Times New Roman';color:#000000;background-color:#ffffff;font-weight:400" class="ContentPasted0">Instituto de Biomedicina de Sevilla(IBIS)</span></p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>De:</b> STEPHAN MORATTI <smoratti@psi.ucm.es><br>
<b>Enviado:</b> jueves, 17 de noviembre de 2022 14:44<br>
<b>Para:</b> FieldTrip discussion list <fieldtrip@science.ru.nl><br>
<b>Cc:</b> FRANCISCO JAVIER GÓMEZ CAMPOS <fjgomez-ibis@us.es><br>
<b>Asunto:</b> Re: [FieldTrip] Help with ft_sourcestatistics</font>
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<div dir="ltr">Dear Francisco,
<div><br>
</div>
<div>It seems that in your source data you probably have the average across subjects, but the individual source data for each subject is missing. You may store them in individual cells and then submit these cells to the source statistics.</div>
<div><br>
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<div>Best,</div>
<div><br>
</div>
<div>Stephan</div>
<div><br>
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<div dir="ltr" class="x_gmail_attr">El jue, 17 nov 2022 a las 11:32, FRANCISCO JAVIER GÓMEZ CAMPOS via fieldtrip (<<a href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a>>) escribió:<br>
</div>
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Dear community,<br>
</div>
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<div>I am having problems using the ft_sourcestatistics function. I would like to use this function</div>
<div>to conduct a within-subject analysis to establish which areas show differences between two</div>
<div>experimental conditions. I mainly have doubts about two aspects, the first one is about how to</div>
<div>attach the source analysis data, and the second one is about the design of the design matrix.</div>
<div><br>
</div>
<div>Regarding the data coming from the source analysis, I have the sources separated by</div>
<div>conditions (obtained by following this tutorial <a href="https://www.fieldtriptoolbox.org/tutorial/beamformer/" target="_blank">
https://www.fieldtriptoolbox.org/tutorial/beamformer/</a>):</div>
<div><br>
</div>
<div>Source analysis data for each condition:</div>
<blockquote style="margin-top:0px; margin-bottom:0px">
<div>freq: 4.8302</div>
<div>cfg: [1×1 struct]</div>
<div>dim: [85 110 132]</div>
<div>inside: [1234200×1 logical]</div>
<div>pos: [1234200×3 double]</div>
<div>method: 'average'</div>
<div>avg: [1×1 struct]</div>
</blockquote>
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<div><br>
</div>
<div>avg:</div>
<blockquote style="margin-top:0px; margin-bottom:0px">
<div>pow: [1234200×1 double]</div>
<div>noise: [1234200×1 double]</div>
<div>filter: {1234200×1 cell}</div>
<div>label: {61×1 cell}</div>
<div>filterdimord: '{pos}_ori_chan'</div>
</blockquote>
</blockquote>
<div><br>
</div>
<div>The code I use is the following (based on this code in this tutorial</div>
<div><a href="https://www.fieldtriptoolbox.org/example/source_statistics/" target="_blank">https://www.fieldtriptoolbox.org/example/source_statistics/</a> ) :</div>
<div><br>
</div>
<blockquote style="margin-top:0px; margin-bottom:0px">
<div>design=[1 2]; %for 2 conditions</div>
<div>% run sourcestatistics using cluster based correction %</div>
<div>cfg = [];</div>
<div>cfg.dim = sourceanalysis_condition1(1).dim;</div>
<div><br>
</div>
<div>cfg.method = 'montecarlo';</div>
<div>cfg.statistic = 'ft_statfun_depsamplesT';</div>
<div>cfg.parameter = 'pow';</div>
<div>cfg.correctm = 'cluster';</div>
<div>cfg.numrandomization = 'all';</div>
<div>cfg.alpha = 0.05; % note that this only implies single-sided testing</div>
<div>cfg.tail = 0;</div>
<div>cfg.design(1,:) = [1:length(find(design==1)) 1:length(find(design==2))];</div>
<div>cfg.design(2,:) = design;</div>
<div>cfg.uvar = 1; % row of design matrix that contains unit variable (in this case: trials)</div>
<div>cfg.ivar = 2; % row of design matrix that contains independent variable (the conditions)</div>
<div>stat = ft_sourcestatistics(cfg, sourceanalysis_condition1, sourceanalysis_condition2)</div>
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<div><br>
</div>
<div>When I run this code, I get the following error:</div>
<blockquote style="margin-top:0px; margin-bottom:0px">
<div>Error using ft_statfun_depsamplesT (line 83)</div>
<div>The data must contain at least two units of observation (trials or subjects).</div>
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<div><br>
</div>
<div>I understand that my design matrix and/or the structure of sourceanalysis_condition are</div>
<div>wrong, I have tried different combinations and I cannot find the solution. I hope you can</div>
<div>guide me in this regard so that I can adapt it to the conditions of my study.</div>
<div><br>
</div>
<div>Thanks,</div>
<div>Francisco Javier Gómez,</div>
Instituto de Biomedicina de Sevilla (IBIS)<br>
</div>
</div>
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<font face="monospace, monospace">Stephan Moratti, PhD</font></div>
<div><font face="monospace, monospace">Profesor de Psicología Experimental</font></div>
<div><font face="monospace, monospace">Departamento de Psicología Experimental</font></div>
<div><font face="monospace, monospace">Facultad de Psicología</font></div>
<div><font face="monospace, monospace">Center for Cognitive and Computational Neuroscience</font></div>
<div><font face="monospace, monospace">Universidad Complutense de Madrid</font></div>
<div><font face="monospace, monospace"><a href="mailto:smoratti@ucm.es" target="_blank">smoratti@ucm.es</a></font></div>
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