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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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1answer
61 views

How to test in SPSS: categorical with continuous predictor and categorical response?

Edited: I'm a statistics newbie, so please be gentle I'm trying to figure out what test to use to analyze a categorical concurrent with continuous predictor for a categorical response. For example:...
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2answers
2k views

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 ...
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1answer
404 views

Quasi-separation when running Cox regression comparing 3 risk groups?

This is my first post here, so please bear with me! I'm comparing several biomarkers with Kaplan-Meier curves and calculating hazard ratios for different risk groups (defined by a certain, well ...
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1answer
79 views

Coefficients in discrete proportional hazards model

I am aware of the rationale behind taking the exponentiated coefficients in a proportional hazards model as representing change in hazard per unit change in the corresponding predictor. This also ...
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0answers
154 views

Cox regression slope - understanding the sign of the slope

I am using the coxme package in R to perform mixed effect cox regression analysis, and would greatly appreciate some advice on how to interpret the regression ...
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1answer
212 views

If the fitted hazard ratio from a Cox model is approximately 1, does that mean the covariate is not significant?

Does a hazard ratio nearly 1 indicate that the covariate's effect on survival time is 0? If so would the corresponding p-value routinely indicate statistical insignificance? In other words, can a ...
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1answer
4k views

Determine if a time-dependent Cox model is appropriate

Before the description, here are my questions (1) Is the set-up of my time-dependent data correct? (2) Are the ways I run my Cox proportional hazard model with a time-dependent variable/ non time-...
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1answer
2k views

Interpret hazard ratio that has huge value

I run a coxph model in R using survival package. Here's the output ...
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1answer
528 views

Expectation of a hazard rate

I need to estimate the expectation of a hazard function, $E[h(x)]$. For instance, for the exponential distribution the result is equal $\lambda$ $$E[h(x)] = \int_0^\infty \! h(x)f(x)\mathrm{d}x = \...
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1answer
691 views

Schoenfeld residual test for model with time varying coefficients?

I'm working with the survival package in R. I fit a Cox proportional hazard model (coxph) and did a scaled Schoenfeld residual test (...
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1answer
45 views

Applying Cox's Porportional Hazard model

I have a dataset on two groups. Group 1 (18 subjects) and group 2 (5 subjects). Each subject in the groups had to perform a number of tasks which was timed. The time restriction was 60 seconds. If ...
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1answer
382 views

What kind of model should I use for churn risk prediction?

I have a data set containing many client's id, and its behavior characteristics measured each month before churn or censored. Data looks like: id || lifetime period || folow-up time before churn of ...
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1answer
243 views

Validity of PH test using Schoenfeld residuals from Cox model on parametric models

I need to use parametric models to model survival data. If the PH assumption holds, I would fit the data for my two intervention groups using a single covariate for treatment effect. I fit a Cox PH ...
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1answer
2k views

time varying coefficients in cox proportional hazard model

I am trying to fit a coxph model in R. The study can be described as follows: I have a very large dataset, in counting process form, containing whether or not someone responded to a survey or not. ...
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1answer
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 ...
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2answers
805 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 ...