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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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### How is the combined effect of explanatory variables calculated for Cox proportional hazard model? [on hold]

I am just learning about the use of Cox proportional hazard model. As I understand it if I feed in the data and 2 explanatory variables, I would get the hazard ratio for each variable with the other ...
22 views

### Continuous Variable No Longer Follows PH Assumption When Categorized

I am creating a cox regression model with multiple covariates. I have two models: model A contains my variable of interest in its original continuous form, and model B contains my variable of ...
153 views

### Interpretation of Cox Hazard Model with quadratic term

I am having trouble finding information on how to interpret coxph model hazard ratios with a quadratic term. Some of my variables are continuous count data, whereas others are continuous percentages. ...
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### Expressing a hazard function with a Cox proportional hazards model

I'm trying to wrap my head around Cox models as well as how to express them in the form of hazard functions when you have both categorical AND numeric covariates. I need some assistance with this ...
182 views

### Cox Proportional-Hazards Regression vs. Regression modeling of competing risk using Fine and Gray

30000 patients all have one diagnosis in common, 3000 of them have been exposed to a potential risk factor before the common diagnosis. 1500 patients develop a malignancy after the common diagnosis. ...
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### Simulate recurrent events data where last observation is censored

I would like to simulate a recurrent events dataset for survival analysis with cox regression in R. The data should have the following properties: multiple, varying number of observations per ID only ...
21 views

### Hazard ratio endpoint vs Odds ratio

This study (https://academic.oup.com/cid/article/65/1/100/3097834) seems to conduct a cox proportional hazard regression on survival data, but reports hazard ratios for 30- and 90-day mortality: ...
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### What are the hazard ratios in this plot referring to?

With the following code in R, I created this graph: ...
63 views

### How to model the Hazard Rate?

I'm interested in modeling the Hazard Rate $\lambda$ from a Survival dataset so I can calculate the Cumulative Distribution $F(t)=1-e^{-\lambda t}$ but I'm not sure how to go about computing $\lambda$...
116 views

### Schoenfeld test (cox.zph) shows no covariate violates PH assumption but global test suggests whole model does (p<0.001). What to do?

Using cox.zph (part of the survival package), I find that no covariate violates the PH assumption in a Cox regression model (p > ...
37 views

### Is the Cumulative Hazard Function simply estimated using the Empirical CDF?

I'm just starting to learn about Survival Analysis and I understand the theoretical proofs but I'm still unclear about how to do some of the estimations practically.
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### Cox Proportional Hazard calibration with same it's meant to predict

I want to model time to churn with a Cox Proportional Hazard model and use it to predict people likely to churn. The question I have is how valid is to calibrate the model with the same people I want ...
28 views

### Days Between Visits Model

I have a dataset from a digital service on a user-level and want to model the decrease in visits and usage over time. I want to explain the decrease (or increase) with the activities a customer ...
28 views