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# Questions tagged [proportional-hazards]

Proportional hazards is an assumption of the Cox proportional hazards model of survival analysis and some other models as well. The assumption is that a linear increase in the predictor will have a uniform multiplicative relationship with the hazard.

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### Testing proportional hazards assumption in parametric models

I'm aware of testing the proportional hazards assumption in the context of the Cox PH models, but I haven't encountered anything relating to parametric models? Is there a feasible way to test the PH ...
4k views

### Recommendations for Non-Proportional Hazards

This is an issue that has plagued me for a long time and I have found no good answers in textbooks, Google, or Stack Exchange. I have data set of >100,000 patients for which four treatments are ...
655 views

### Does the proportional hazards assumption still matter if the covariate is time-dependent?

If I estimate a Cox Proportional Hazards model and my covariate of interest is dependent (continuous or categorical), does the proportional hazards assumption still matter? I recently went to a ...
1k views

### How can I obtain prediction intervals for survival prediction in the Cox model?

Prediction of survival times in Cox proportional hazard regression model has been discussed here. In R, survfit::survival using ...
1k views

### Expected survival time for Weibull proportional hazards model with R's predict.survreg

The predictions for a Weibull proportional hazards model from R's predict.survreg() are not the expected survival times. Please help me understand this behaviour. ...
80 views

### How to calculate Hazard ratio if there are more than two Kaplan-Meier curves

A population was sub-typed into 4 groups and Kaplan-Meier curves were plotted. If there were only two survival curves then the hazard ratio would be the hazard of one group divided by the hazard of ...
882 views

### Proportional hazards vs proportional odds for modeling ordinal data

When working with ordinal response data, we can use a proportional odds model to calculate the log odds in favor of one category over another. Often we use a logit link yielding the following model: ...
427 views

### Cox proportional model with multiple failures for same subjects

I have a dataset that I'm trying to model using Cox proportional hazard models. The data include patient IDs and several attributes about the patients (including time till failure). Due to the nature ...
3k views

### Can a Cox proportional hazards model be used on general left-censored data (i.e. non-survival data)?

A familiar problem in applied science is having censored data, in particular left-censored data arising due to an assay or piece of equipment having a lower limit of detection (LOD). Assuming a ...
804 views

### Error term interpretation in the Cox PH model

I am preparing a presentation on Survival Analysis models, with specific focus on the Cox model. Suppose I am in the simple bivariate survival analysis case (with $x_1$ and $x_2$). The Cox model ...