Can a survival analysis model with poor model fit still be useful in reporting? I have set up a time-varying survival analysis model (Cox regression in SAS), and have found it to have poor model fit. I tested for goodness of fit using Cox-Snell residuals, and also the Gronnesby and Borgan test. Assuming proportional hazards assumptions hold, and other diagnostics (multicollinearity, confounding, interaction) are being accounted and controlled for, what are the implications of this model? Are there any suggested next steps in either reporting or potentially resolving fit issues?