Periodogram-based-40 estimators of the spectral density are known to exhibit distorted behavior in neighborhoods origin case so-called low frequency contamination, mimicking long-range dependence. This note quantifies estimator based on autoregressive approximations order increasing with sample size. Not surprisingly, is not consistent at under ignored changes mean, but turns out be non-zero fr...

Longitudinal change in five cognitive abilities was investigated to determine if the direction or magnitude of change was related to the individual's ability level. Adults between 18 and 97 years of age performed three versions of 16 cognitive tests on two occasions separated by an average of 2.7 years. In order to control for influences associated with regression toward the mean, level of abil...