All Questions
Tagged with cox-model proportional-hazards
227 questions
3
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1
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Do multiple observations per individual imply pseudo-replication in time-varying Cox proportional survival model (coxme in R)?
I’m running a survival analysis using a cox mixed-effect proportional hazard model with time-varying covariates (using package and function coxme in R).
My ...
- 33
1
vote
0
answers
410
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Time scale in survival analysis
I am doing a churn analysis of some bank customers with survival analysis.
Right now I am using the customers' years in the bank [0;17] as time scale, and then use the customers' entry age as a ...
- 31
1
vote
1
answer
383
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How does time factor into Cox regression or a Cox proportional hazards model?
The hazard function for the Cox proportional hazard model is written as follows.
$$\lambda(t|X_i) = \lambda_0(t)\exp(\beta_1X_{i1} + \cdots + \beta_pX_{ip}) = \lambda_0(t)\exp(X_i \cdot \beta)$$
I ...
- 1,400
4
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3
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6k
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Proportional hazards assumption and time-dependent covariates
Is there a way to check that the proportional hazards assumption is correct for a Cox model with time-varying covariates ?
- 603
2
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0
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1k
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Predicting Lifetimes using CoxPH
I have a dataset of about 9k rows and 60 features (columns). I have a binary status column (1 - dead, 0 - alive) and a lifetime column in days which is right censored. I am currently using the cox-PH ...
- 121
1
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0
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95
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Cox proportional hazard - can hazard be treated as instantaneous probability?
I'm doing a question on cox proportional hazard models that at the very last step leaps from hazards to probabilities, and I'm not sure how it does this. I've paraphrased it below to keep it simple, ...
- 2,589
2
votes
1
answer
990
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Interpretation of hazard rate for multiple failures
I'm trying to run survival analysis of Cox proportional model with panel data that consists of IDs and time variable. Each individuals are allowed to fail more than once in the sample period. My ...
- 201
4
votes
1
answer
2k
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How to manually calculate `survfit` in cox hazard model?
Here is a toy survival model with age only. But I still do not know how the surv numbers in survfit are calculated: $\exp(\beta ...
- 37.3k
10
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2
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6k
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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 ...
- 123
6
votes
1
answer
3k
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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 ...
- 6,724
2
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1
answer
616
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Help with a Cox Proportional Hazard Simulation in R
I am trying to follow along with a scientific journal. I am not used to running simulations so I could use a little help in R.
Here is the simulation from the paper.
For each experiment, we ...
- 2,051
4
votes
1
answer
2k
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Proportional hazards assumption: trouble interpreting my results for cox.zph() function in R
I am testing my proportional hazards assumption in R using the cox.zph() function:
...
- 73
2
votes
1
answer
668
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How to cope with non-proportionality?
I run a Cox model with 2 covariates, in addition to the variable of interest.
For one covariate, the assumption of proportional hazards is violated.
I know different methods developed to cope with non ...
- 21
5
votes
1
answer
1k
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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 ...
- 51
6
votes
2
answers
2k
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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 ...
- 61
2
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0
answers
214
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How to interpret insignificance of time-varying coefficient and main effect
I have a survival-time dataset where entities (countries) are measured at discrete intervals (years). I'm interested in examining the effect of some fixed treatments (i.e. ones that occur at the ...
- 143
3
votes
1
answer
1k
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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 ...
- 31
1
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0
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562
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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 ...
- 892
0
votes
1
answer
504
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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 ...
- 285
3
votes
1
answer
5k
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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-...
- 285
3
votes
1
answer
2k
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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 (...
- 1,096
1
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1
answer
50
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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 ...
- 35
3
votes
1
answer
595
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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 ...
- 31
1
vote
1
answer
442
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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 ...
- 11
6
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1
answer
4k
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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. ...
- 163
11
votes
2
answers
11k
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Extended Cox model and cox.zph
I have previously had experience only with Cox PH model and its assumptions checking.
Now for the first time I have my clients data with most of the covariates varying in time, only a few are fixed ...
- 111
7
votes
2
answers
1k
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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 ...
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