Raudenbush, 1992), and the ability to specify separate error terms at each level of nesting. Multilevel modeling is robust to missing observations, whereas repeated-measures ANOVA requires that missing values be interpolated or aggregated across, or that the subject’s data be discarded. Thus, assuming reasonably large samples (n > 10 + k) this approach generally yields greater power than ANOVA (Baguley, 2004). Based on these considerations, the current data were analyzed with hierarchical linear modeling (HLM) using SAS PROC MIXED (see Bryk & Raudenbush, 1992).2 Measurements of voltage at each electrode site for each condition were nested within subjects. Nuisance variance between subjects was modeled by including a random intercept of subject.
