Figure 2:

Internal validation of the model in (A) LHS smokers (RMSE 0.24, actual 95% coverage probability 94%) and (B) LHS sustained quitters (RMSE 0.24, actual 95% coverage probability 93%). External validation of the model in (C) EUROSCOP smokers (EUROSCOP included only smokers) (RMSE 0.22, actual 95% coverage probability 91%), (D) PanCan smokers (RMSE 0.25, actual 95% coverage probability 90%) and (E) PanCan sustained quitters (RMSE 0.19, actual 95% coverage probability 93%). Note: EUROSCOP = European Respiratory Society Study on Chronic Obstructive Pulmonary Disease, FEV₁ = forced expiratory volume in 1 second, LHS = Lung Health Study, PanCan = Pan-Canadian Early Detection of Lung Cancer Study, RMSE = root mean squared error.