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<body class='hmmessage'><div dir='ltr'>Dear Eric Maris or other fieldtrippers, <div><br></div><div>In my experiment (a 2x2x6 design) I want to test whether ERP waveforms are significant different between conditions. There is no <i>a priori</i> assumption about the effects.</div><div>In this experiment I apply a somatosensory stimulus on both arms before and after an intervention on one arm. The somatosensory stimulus consists of 6 different intensities. So it is a within-subject design with 3 factors: Time (T0 and T1), Arm (intervention, control) and Intensity (6 different intensities).</div><div><br></div><div>I'm interested in the MAIN effect of INTENSITY, and the INTERACTION effects (TIME x ARM) and (TIME x ARM x INTENSITY).</div><div>For the Interaction effect TIME x ARM, I first calculated difference-waves (postcontrol - precontrol and postintervention - preintervention) in Matlab en then applied the permutation test on these difference-waves to test whether the two arms are different. I hope this is correct?</div><div><br></div><div>But now my question, how to test the TIME x ARM x INTENSITY interaction? </div><div>One possibility might be to calculate an ANOVA F statistic for this interaction effect (so perform a full factorial ANOVA) and perform the permutation test? Is this justified?</div><div><br></div><div>Very much thanks,</div><div>Best wishes,</div><div>Emanuel</div><div><br></div><div><br></div><div><br></div><div><br></div> </div></body>
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