Figure 1
Graphic illustrations of random error distribution for CE AREA and CoP ML. Random error (i.e. individual test-retest differences) is plotted against the individual means of the two sessions, both in eyes open and eyes closed conditions. For CEAREA(A) the larger random error for higher mean values is suggestive of heteroscedasticity. For CoPML(B) the random error is rather constant whatever the mean, which suggests absence of heteroscedasticity.