Coefficients of variation (CV) of change scores across individuals were calculated for each ROI determined from each method, where the CV=SD/mean of the 15 tissue ROIs. CVs provide a measure of the dispersion of the values with respect to the mean expressed as a percentage and serve as an index of measurement precision. As such, the CV is an error estimate, which can reflect parcellation, registration, movement, and other sources of error. Mean CVs across the 15 tissue ROIs were derived for each registration method and compared with Wilcoxon tests. The same analysis procedure was conducted for CSF volumes of the ventricles and cortical sulci. The method with the lower CVs was then chosen to describe regional brain changes with development using paired t-tests or Mann-Whitney U-tests and Pearson correlations or Spearman rank order tests between change in regional brain volumes and change in Tanner stage.
