All Questions
Tagged with cox-model regression
38 questions with no upvoted or accepted answers
5
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How to better understand when to use Weibull AFT versus Cox Model for Failure Data
I am struggling to understand when I should consider using a Cox regression model versus using a Weibull AFT model to predict the end of life of mechanical components.
I have tried to apply the Cox ...
- 95
3
votes
0
answers
65
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Approach to a complex survival analysis
Hello and thanks for reading!
I'm a student who has unfortunately 'designed' quite a complicated experiment which I'm struggling to analyse statistically. I do like statistics but my experience is ...
- 31
2
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0
answers
226
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How to model an interaction in a propensity-score matched dataset
Suppose I am performing a propensity score matched analysis using the MatchIt package in R, following the example reported here: https://kosukeimai.github.io/...
- 706
2
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0
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110
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Check if PH or AFT model should be fit
It is unclear to me when it is appropriate to fit an accelerated failure time (AFT) model rather than a proportional hazard (PH) model.
I've tried googling and it appears as though PH models are ...
- 635
2
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0
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83
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Results of a survival analysis change when converting the data to counting process format
Consider the following simple example:
...
- 3,433
2
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0
answers
214
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independence assumption on events in Cox model
In the wikipedia article on the Cox model, in the development of the partial likelihood, it is mentioned that the different subjects are treated "as if they were statistically independent." Is this in ...
- 576
2
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0
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583
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Cox-Snell plot for Cox regression model
Is this Cox-Snell plot of my Cox regression model acceptable?
Or should I keep on looking for a better one?
- 31
2
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0
answers
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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44
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Count data with time-varying covariates
One way to model count data is to simply count up the number of events as the outcome with an offset of observation time if this varies between people. I presume it's also possible to model count data ...
- 857
1
vote
1
answer
299
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Cox Regression model with time-dependent covariates - violated assumption of proportional hazards (PH)
I am currently performing some Cox regression models. The image attached shows a Schönfeld residual based on one of the cox models with a significant p-value which means that the proportional hazards ...
user389026
1
vote
1
answer
198
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Robust standard errors with splines
I realize that large changes in model results between using robust and non-robust standard errors can suggest a misspecified model.
My case refers to using a Cox regression and I have experimented ...
- 409
1
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0
answers
56
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Different results for PH for dummy encoding versus not in Cox regression
I've been running a Cox regression with a dummy encoded dataset. For certain reasons, I tried doing the same procedure by using factor in ...
- 409
1
vote
1
answer
143
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Presentation of a 3x3 categorical interaction for Cox proportional hazards regression using RMS package
I wanted to verify my presentation of a 3x3 interaction of two categorical variables var1 (exposure of interest) and var2 (effect modifier of interest) using the rms...
- 11
1
vote
1
answer
31
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Should I use cox regression for this?
Should I be using cox regression for this?
I am analyzing the performance of a tennis player. I want to understand how long on average his performance starts to drop during a match.
I indicate an ...
- 11
1
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0
answers
47
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How can I determine whether my Cox regression analysis have enough power to conclude an outcome
I have 159 tumor patients, of which I know several parameters: age, sex, stage, ... and x.
X is a continuous covariate corresponding to the percentage of tumor cells currently dividing (biological ...
- 259
1
vote
0
answers
164
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Survival analysis: how to account for immortal time with time-dependent exposure
I am working on a survival analysis to look at time to preterm birth (birth before 37 weeks). I have a time-dependent exposure that can occur anytime at or after 28 weeks, defined using a heaviside ...
- 75
1
vote
1
answer
106
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Cox Regression and Linkage Disequilibrium
I'm trying to figure out the best way to account for linkage disequilibrium in a cox regression, and would really appreciate your advice. I'm testing the effect of a particular allele on overall ...
- 41
1
vote
0
answers
66
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Cox Regression Model for toxicity
I'm trying to evaluate the toxicity of a certain treatment over time. I have 2 independent groups and I apply a treatment to one, and nothing to the second one. I thought about using logistic ...
- 41
1
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0
answers
854
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What could be the reasons for why re-scaling variables used in regression helps model performance?
There's already an excellent post on standardizing values used for regression here. In this post, I am using Cox Regression (Cox Proportional Hazard model) with the lifelines Python library. Now, one ...
- 1,400
1
vote
0
answers
321
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Different hazard ratios in Cox model, depending on which dummy is omitted?
I'm using a Cox survival analysis model in Stata. My covariates include a series of mutually-exclusive dummies. As in other regression models, I leave one out as a reference.
If I change the ...
- 604
1
vote
0
answers
48
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Survival curve of Cox model
I am investigating factors associated with early discharge (vs full stay) in hospital amongst a cohort. Early discharge is the event. This is not an intervention study. I have 7 factors in the model, ...
- 165
1
vote
0
answers
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
1
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0
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53
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How do you calculate the compared populations in cox hazard ratio problems?
Take a look at the following open-access paper
http://www.ncbi.nlm.nih.gov/pubmed/26506242
I've tried doing cox regression in both R and SPSS but I cannot get ...
- 213
1
vote
0
answers
240
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Modelling retirement of employees by age where only data of very few years are available
We want to model the retirement of employees. We have data on a yearly base for about 20,000 employees by age and some other properties.
There are two questions:
Suitable Approach
In most cases we ...
- 241
1
vote
0
answers
117
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How to do Cox regression if we have a variable which violates an assumption?
Is there a better way than stratification to do Cox regression for two variables, one qualitative and other quantitative, the qualitative (and more important one) violates an assumption of Cox ...
- 11
1
vote
0
answers
41
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Cox regression to see if distribution of disease predicts survival
I'm working with clinical data from a few hundred patients. Every patient was measured at 6 different timepoints with regular intervals.
Each patient is assessed on 3 different domains and given a ...
- 11
0
votes
1
answer
209
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Lifelines-CoxTimeVaryingFitter for Multistate Survival Analysis
I am new to survival analysis and cox regression, and have limited statistical background. I have time-to event data for a multistate survival model and I want to fit a cox model for each transition ...
- 57
0
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0
answers
46
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Constructing nomogram from approximate model in Regression Modelling Strategies
In section 19.5 in Regression Modelling Strategies by Frank Harrell we make an approximate model using linear regression with ols. Since this is an ols object we have to calculate survival quantities ...
- 101
0
votes
0
answers
956
views
Robust standard errors in Cox survival analysis
The final step of running a Cox model I've been working on involves performing log-likelihood ratio tests to check the significance of each predictor to the model. I'd like to do this using ...
- 409
0
votes
0
answers
135
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Overall effect for non-binary categorical variable, Cox
There are many great answers on Cross-Validated explaining that the p-values for cox.zph (or other regression models) in R refer ...
- 409
0
votes
0
answers
353
views
Huge confidence intervals in a covariate in regression
I am running a Cox regression for a large (100k) dataset with 135 variables after dummy encoding.
Most of the coefficients are reasonable and the confidence intervals are not large. However, for one ...
- 409
0
votes
1
answer
416
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When having non-proportional hazards, should I use stratified Cox by time or Logrank tests within periods?
My data have non-proportional hazards with clear separation. Should I handle it via stratified Cox regression or using separate Log-rank test within subsets?
I will use R only to illustrate.
I want to ...
- 23
0
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0
answers
61
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3 terms interaction in Cox PH model
'''
coxph(formula = Surv(time, hyper) ~ age + drink + smoke + sodium * tchl * BMI, data = male)
coxph(formula = Surv(time, hyper) ~ age + drink + smoke + sodium * tchl * BMI, data = female)
The 3-...
- 37
0
votes
1
answer
150
views
What should I do if only 1 covariate violate the proportionality assumption in Cox PH?
Can I still use Cox PH model? or I will have to find a non-PH model? What are the available models that can be used here?
Schoenfeld residuals (using ...
- 227
0
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0
answers
20
views
In cox model, can the hemoglobin and homoglobin group be put in the same model?
fit.tdc <-
coxph(Surv(t1,t2,status) ~ Hemoglobingroup + hemoglobin + sex +
diabet + cluster(id), data)
fit.tdc
Can the hemoglobin and hemoglobin group be put ...
- 11
0
votes
0
answers
191
views
weird outlier in a cox regression model
I'm using normal deviate residual to identify outliers, and I'm confused that my plot seems to suggest that there are unreasonably a lot of outliers...? Has anyone seen something like this?
...
- 381
0
votes
0
answers
45
views
Estimating death based on repeating sequence?
Currently I'm working on a project, and I reading up on Survival Regression with Cox’s proportional hazard model, which looks like it will work to answer the questions I want to ask.
My issue is ...
- 101
0
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0
answers
32
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Can I incorporate differencing into a (Cox) survival model?
I am predicting college student dropout with a Cox model. I believe that a declining grade point average (GPA) is predictive of dropout, and I want to incorporate this into my model. I'm looking for ...
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