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<font size="4" class="">Hi Matt,</font>
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<div class=""><font size="4" class="">I am not sure what you’re after - because your question is not fully well-posed - but I think that the actual question is about how the ‘pow’ field is computed, and how this differs between the plain output from ft_sourceanalysis
(when using cfg.method = ‘mne’), and ft_sourcedescriptives (when using as input the output of ft_sourceanalysis, and using cfg.projectmom = ‘yes’).</font></div>
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<div class=""><font size="4" class="">After ft_sourceanalysis (with cfg.method = ‘mne’) you get a source-structure with source.avg.pow. The pow is the magnitude (squared) of the dipole moment over time, obtained by squaring and summing across the three cardinal
x/y/z orientations. </font></div>
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<div class=""><font size="4" class="">After ft_sourcedescriptives (with cfg.method = ‘mom’, which only works if previously ft_sourceanalysis has been called with cfg.mne.projectmom = ‘yes’) the pow-field of the output contains the magnitude squared dipole moment
along the principal axis of the dipole’s activity (i.e. estimated by means of an svd). </font></div>
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<div class=""><font size="4" class="">So, in short, the difference between the 2 ‘pow’s is that the first one assumes a model where the dipole is rotating over time, whereas the second one models the dipole’s activity under the assumption that it has a fixed
orientation over time.</font></div>
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<div class=""><font size="4" class="">Best wishes,</font></div>
<div class=""><font size="4" class="">Jan-Mathijs</font></div>
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<div class="">On 3 Jul 2021, at 00:27, Matt Moradi via fieldtrip <<a href="mailto:fieldtrip@science.ru.nl" class="">fieldtrip@science.ru.nl</a>> wrote:</div>
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Hi Experts,</div>
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What is the main difference between<span class="gmail-Apple-converted-space"> output of ft_sourceanalysis and the ft_sourcedescriptive? we are using them with MNE method to get the source of the difference between two ERPs and we cannot quite figure out if
we are feeding the correct parameters ...</span></div>
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<span class="gmail-Apple-converted-space">at the end of this page at:</span></div>
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<span class="gmail-Apple-converted-space"><a href="https://urldefense.com/v3/__https://www.fieldtriptoolbox.org/tutorial/minimumnormestimate/__;!!HJOPV4FYYWzcc1jazlU!v0m9C0651gDPW_WeBCkmGdDM0U5aX_3rC3P7iMEkPzbEp5Y3IbwOSyXQjl3nwwM2Zh5aczYrSJz-rUs$" class="">https://www.fieldtriptoolbox.org/tutorial/minimumnormestimate/</a></span></div>
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<div style="font-family: Calibri, sans-serif; margin: 0in;" class=""><span class="gmail-Apple-converted-space" style="font-size:11pt">They are plotting the difference between the two ERPs from output of ft_sourcedescritive with the projectmom option, but doing
the same subtraction (</span><span style="font-family:Helvetica;color:rgb(7,55,99)" class="">sdDIFF.avg.pow = sdFIC.avg.pow - sdFC.avg.pow</span><span style="font-size:11px;font-family:Helvetica;color:rgb(7,55,99)" class="">)</span></div>
<div style="margin: 0in;" class=""><span class="gmail-Apple-converted-space"><font color="#073763" face="tahoma, sans-serif" class=""><span style="caret-color: rgb(7, 55, 99);" class="">with the avg.pow</span></font><font face="Calibri, sans-serif" class=""><span style="caret-color: rgb(0, 0, 0);" class=""> </span><span style="font-size:11pt" class="">output
from ft_sourceanalysis </span></font>gives<font face="Calibri, sans-serif" class=""><span style="font-size:11pt" class=""> a
</span></font>different<font face="Calibri, sans-serif" class=""><span style="font-size:11pt" class=""> solution.</span></font></span></div>
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<span class="gmail-Apple-converted-space">Appreciate any thoughts!</span></div>
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<span class="gmail-Apple-converted-space">Thanks,</span></div>
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<span class="gmail-Apple-converted-space">Matt</span></div>
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<span style="color:rgb(34,34,34);font-family:Arial,Helvetica,sans-serif;font-size:small" class="">-- </span></div>
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<div class=""><span style="color:rgb(61,133,198)" class=""><span style="background-color:rgb(255,255,255)" class=""><span style="font-family:tahoma,sans-serif" class=""><i class="">Matt </i></span></span></span></div>
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