and last in the sequence); models centered one year apart share at least 86% of their data and models two years apart share at least 75%, so that there is considerable overlap in the data used for calculation in nearby ages. The regression is weighted so that data near the center age counts more in determining the result than data further away from the center. Each of the six dependent variables, the theta ERO power values at each electrode and each modality, is modeled separately in order to simplify the interpretation of the regression analysis. This methodology is adapted from the work of Cleveland (1979); Cleveland and Devlin (1988); Gasser et al. (1984a,b); Ramsay and Silverman (2002); Gasser et al. (2004); Molinari and Gasser (2004).
