I am conducting a 2 (stimulus type) x 2 (response mode) within-subjects ANOVA on Response Times on a computer task and I am having trouble making a decision about a particular kind of outlier.
I have one participant for whom each of the four means used in the analysis are not outliers.
However, the difference between Response Time means between the two stimulus types for this participant is 3 SDs above the mean for the sample. Including this one participant influences my results quite a bit as they are showing a main effect for stimulus type.
Is there a process to identify and remove outliers such as this?