Introduction In Part 1 of this series, we showed that six different methods for estimating individual means—James-Stein, classical true score estimation, empirical Bayes, ridge regression, and hierarchical models (frequentist and Bayesian)—all converge on the same fundamental principle: shrink each individual’s estimate toward the group mean by a factor of \(\sigma^2_{\text{pop}} / (\sigma^2_{\text{pop}} + \sigma^2_{\text{obs}}/n)\).