Figure 4.

Cross-validation of the trained random forest regression on the mixed cohorts of data from other institutes (SMC and SNU). The prediction results on these cohorts using the random forest regression model which had been trained using the main data from Asan Medical Center (AMC) are shown. Results before considering the site bias (A), results after correcting the site bias (B). The bias was assumed to be linear and thus corrected using the linear model which was performed using a leave-one-out approach (per site) to determine the coefficient of the slop for the test patient. The inverse transformation was applied to the determined coefficient to obtain the new result in the right panel.