Data-driven smooth tests of the proportional hazards assumption
- 4 November 2006
- journal article
- Published by Springer Science and Business Media LLC in Lifetime Data Analysis
- Vol. 13 (1), 1-16
- https://doi.org/10.1007/s10985-006-9027-8
Abstract
A new test of the proportional hazards assumption in the Cox model is proposed. The idea is based on Neyman’s smooth tests. The Cox model with proportional hazards (i.e. time-constant covariate effects) is embedded in a model with a smoothly time-varying covariate effect that is expressed as a combination of some basis functions (e.g., Legendre polynomials, cosines). Then the smooth test is the score test for significance of these artificial covariates. Furthermore, we apply a modification of Schwarz’s selection rule to choosing the dimension of the smooth model (the number of the basis functions). The score test is then used in the selected model. In a simulation study, we compare the proposed tests with standard tests based on the score process.Keywords
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