%0 Journal Article %T Using fractional polynomials and restricted cubic splines to model non‐proportional hazards or time‐varying covariate effects in the Cox regression model %A Austin, Peter C. %A Fang, Jiming %A Lee, Douglas S. %J Statistics in Medicine %V 41 %N 3 %P 612-624 %@ 0277-6715 %D 2022-02-10 %I Wiley Subscription Services, Inc., A Wiley Company %~ DeepDyve