Figure 2

Schoenfeld residuals for physical activity in the multivariate Cox model for the example case-cohort study of colorectal cancer risk, using insulin levels as the primary exposure variable. For variable definitions, please see foot note for Table 3. The solid smooth line is the estimated lowess smoothed curve of G(t), i.e., the time-dependent departure of proportionality, and the dotted lines are the estimated confidence bands.