<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Cher Seb,<div><br></div><div>In order to be able to compute a single subject T-statistic on the TFR you indeed need to specify cfg.keeptrials = 'yes', prior to calling ft_freqanalysis. Are you absolutely sure that you did this? If so, we need to look into this. Could you create yourself an account on our bugzilla file-server (<a href="http://bugzilla.fcdonders.nl">bugzilla.fcdonders.nl</a>) and file this as a bug. Just copy and paste your e-mail message and also upload some script+data facilitating the reproduction of the problem?</div><div><br></div><div>Cheers,</div><div><br></div><div>Jan-Mathijs</div><div><br><div><div>On Dec 7, 2011, at 7:52 AM, <a href="mailto:miellet@psy.gla.ac.uk">miellet@psy.gla.ac.uk</a> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>Hello,<br>I've got problems doing second-level stats with TFR because of the data structure.<br>I previously did it with ERF and didn't experience any difficulty. I'm just comparing 2 conditions so the design is very simple. The dimord for ERF was rpt_chan_time so I had access to the different trials.<br>For ERF, I computed individual t-values between my conditions and across trials; then averaged the result across participants and compared the grand-average to zero. Do you think this strategy makes sense?<br>For TFR, the dimord is chan_freq_time (with cfg.keeptrials='yes', before or after ft_freqbaseline). Obviously I don't want to compute the individual t-values across channels, freq bands or time points but across trials.<br>Do you have any idea where I could find this information please? (I look in previous.....previous but couldn't find anything useful. I also specify keeptrials at each step of the process)<br>Thank you very much for your help,<br>Sebastien<br><br>----------------------------------------------<br>Dr. Sébastien Miellet, Lecturer<br><br>Department of Psychology<br>University of Fribourg<br>Faucigny 2<br>1700 Fribourg<br>Switzerland<br><br>tel: +41 26 300 7666<br>----------------------------------------------<br><br><br><br>Quoting Sara Bögels <<a href="mailto:s.bogels@psy.gla.ac.uk">s.bogels@psy.gla.ac.uk</a>>:<br><br><blockquote type="cite">Hi all,<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">I have been trying to do second-level statistical inference (as described in one of the FAQs) on ERFs, but I am not sure whether I am doing everything correctly.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">In the first step I calculate the T-values for the difference between two conditions (twice), which are between items, with ft_timelockstatistics. I put the output of all participants in a cell (called 'stat1a' and 'stat1b'). (I tried to use ft_timelockgrandaverage to combine the subjects together but it needs a field avg).<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Then I use ft_timelockstatistics again but subject level. I first want to look at the difference between the two conditions. This difference is reflected in the T-values of the first step so I create a dummy which is the same as 'stat1' but I replace all the values in the field 'stat' per participant with zeros. Then I call (with appropriate cfg parameters):<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">stat2a = ft_timelockstatistics(cfg,stat1a{:},dummy{:});<br></blockquote><blockquote type="cite">stat2b = ft_timelockstatistics(cfg,stat1b{:},dummy{:});<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">To compare the two differences (stat1a and stat1b) and thereby look at an interaction, I call:<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">stat2a-b = ft_timelockstatistics(cfg,stat1a{:},stat1b{:});<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">I am uncertain whether the dummy works (or is there a way to compare the t-values to zero directly?) and whether the stat1a{:} trick works with ft_timelockstatistics.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Thanks in advance for your answer.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Sara<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">_______________________________________________<br></blockquote><blockquote type="cite">fieldtrip mailing list<br></blockquote><blockquote type="cite"><a href="mailto:fieldtrip@donders.ru.nl">fieldtrip@donders.ru.nl</a><br></blockquote><blockquote type="cite"><a href="http://mailman.science.ru.nl/mailman/listinfo/fieldtrip">http://mailman.science.ru.nl/mailman/listinfo/fieldtrip</a><br></blockquote><blockquote type="cite"><br></blockquote><br><br><br>----------------------------------------------------------------<br> This message was sent using the Web mail system for<br> The University of Glasgow School of Psychology<br>------------------------------------------------------------------<br><br><br><br>_______________________________________________<br>fieldtrip mailing list<br><a href="mailto:fieldtrip@donders.ru.nl">fieldtrip@donders.ru.nl</a><br>http://mailman.science.ru.nl/mailman/listinfo/fieldtrip<br></div></blockquote></div><br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><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">J.Schoffelen@donders.ru.nl</a></div><div>Telephone: +31-24-3614793</div></div></span></div></span></div></span></div></span></div></span></span>
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