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<p class="MsoNormal"><span lang="EN-GB">Dear community,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I am currently working on statistically testing the correlation between EEG data (dependent variable) and quantitative data (independent variable).
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I'm using the ft_statfun_correlationT function to correlate and test the quantitative independent variable (e.g. reaction time), which is one value per subject, with the subject's averaged ERP data (31channelx500timepoints)
(~100 subjects). I used this configuration from the tutorial and it worked well:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal" style="background:#F0F0F0"><i><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#60A0B0;mso-fareast-language:DE">% compute statistics with correlationT</span></i><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:#F0F0F0"><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">cfg
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">=</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE"> [];<o:p></o:p></span></p>
<p class="MsoNormal" style="background:#F0F0F0"><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">cfg</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">.</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">statistic
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">=</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#4070A0;mso-fareast-language:DE">'ft_statfun_correlationT'</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">;<o:p></o:p></span></p>
<p class="MsoNormal" style="background:#F0F0F0"><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">cfg</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">.</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">method
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">=</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#4070A0;mso-fareast-language:DE">'montecarlo'</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">;<o:p></o:p></span></p>
<p class="MsoNormal" style="background:#F0F0F0"><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">cfg</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">.</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">numrandomization
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">=</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#40A070;mso-fareast-language:DE">1000</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">;<o:p></o:p></span></p>
<p class="MsoNormal" style="background:#F0F0F0"><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal" style="background:#F0F0F0"><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">n1
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">=</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#40A070;mso-fareast-language:DE">99</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">;
<o:p></o:p></span></p>
<p class="MsoNormal" style="background:#F0F0F0"><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">design(</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#40A070;mso-fareast-language:DE">1</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">,</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#40A070;mso-fareast-language:DE">1</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">:n1)
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">=</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE"> qualitative_variable; % e.g. [0.25,
0.22, …]<o:p></o:p></span></p>
<p class="MsoNormal" style="background:#F0F0F0"><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">cfg</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">.</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">design
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">=</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE"> design;<o:p></o:p></span></p>
<p class="MsoNormal" style="background:#F0F0F0"><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">cfg</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">.</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">ivar
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">=</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#40A070;mso-fareast-language:DE">1</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">;<o:p></o:p></span></p>
<p class="MsoNormal" style="background:#F0F0F0"><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal" style="background:#F0F0F0"><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE">stat
</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#666666;mso-fareast-language:DE">=</span><span lang="EN-GB" style="font-size:10.0pt;font-family:Consolas;color:#212529;mso-fareast-language:DE"> ft_freqstatistics(cfg, data_brain{:});<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I saw that the t-values are calculated by using this:
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">tstat = rho*(sqrt(nrepl-2))./sqrt((1-rho.^2))<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I'm afraid I don't know much about statistics. But wouldn't it be appropriate to correct for the multiple comparison problem by using a cluster-based approach?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">So I tried to add this to my configuration:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">cfg.alpha = 0.025; <br>
cfg.correcttail = 'alpha'; <br>
cfg.correctm = 'cluster'; <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">cfg.clustertail = 0;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">cfg.clusteralpha = 0.05;<br>
cfg.clusterstatistic = 'maxsum'; <br>
cfg.neighbours = neighbours;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I get the error: <br>
Error using ft_statistics_montecarlo could not determine the parametric critical value for clustering<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Error in ft_timelockstatistics (line 185)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">[stat, cfg] = statmethod(cfg, dat, design);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Is there already a correction for MCP and am I thinking wrongly by using a cluster based approach?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">How is the cfg.numrandomization implemented in this statistic? I may have missed something, but it didn't look like random permutation was being used at all.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Any help would be highly appreciated.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Thank you very much and all the best,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Pia<o:p></o:p></span></p>
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