O'Quigley J, Moreau T
Comput Methods Programs Biomed. 1986 Jun;22(3):253-6. doi: 10.1016/0169-2607(86)90001-5.
A simple test for goodness of fit of the proportional hazards regression model has recently been proposed. This article indicates how a large number of programs in current use to fit this model can be easily adapted to incorporate this goodness of fit statistic.