FIGURE 2.

Simulation experiments investigating harmonization performance as a function of the mixing coefficient in the second batch. PEACE attains lower RMSE than ComBat and is robust to differences in cluster frequency between batches. Top: Histograms of simulated data. Data simulations were based on statistics observed in our PiB DVR dataset, with the two clusters being analogous to PiB– and PiB+ groups. The mixing coefficient was fixed at 50% in the first batch and was varied from 10% to 90% in 20 percentage point increments in the second batch. A low mixing coefficient corresponds to a lower frequency of the first cluster, which is analogous to the PiB– group. Bottom: RMSE of the harmonized values as a function of the mixing coefficient in the second batch (${\varphi }_{b=2,z=1}$). PEACE, Probabilistic Estimation for Across‐batch Compatibility Enhancement; PiB, ¹¹C‐Pittsburgh compound B; RMSE, Root mean square error.