All Questions
134 questions
0
votes
1
answer
23
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What are the differences between PS-match and adjusted Cox regression?
This is more like an extension of the following question: Propensity Score Matching with Cox Regression
I am wondering what are the differences between these:
matching patients with PS and running ...
- 581
0
votes
0
answers
19
views
How to plot hazard ratio from coxph model with tt() term [closed]
This question is related to another that I posted here:
How to visually assess tt() suitability in coxph
If we have a time-varying HR that arises from a time-dependent coefficient because we have ...
- 857
0
votes
0
answers
32
views
How to visually assess tt() suitability in coxph? [closed]
For this example, I am taking cues from the time-dependent survival vignette.
I am interested in understanding how to assess the suitability of a covariate-time interaction using ...
- 857
0
votes
1
answer
86
views
Dealing with categorical variables on cox regression
I am trying to fit a Cox regression model to my time-to event data and have a categorical variable with 5 different levels. If I don't leave one of the levels out, then I will have multicollinearity, ...
- 57
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
5
votes
3
answers
227
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Cox model - unsure of time unit of analysis
I am running a survival analysis (Cox model) on time to event in cancer patients. The start of followup is end of treatment. Tests for the event (recurrence) are performed every 6 months from cancer ...
- 923
0
votes
0
answers
46
views
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
5
votes
2
answers
187
views
Why are linear and spline term estimates so different?
I am working on modelling in an epidemiological setting. I want to estimate the association between an exposure (air pollution) and two event outcomes. To achieve that, I am using a Cox PH model with ...
- 794
1
vote
2
answers
62
views
Interpretation dummy variables Cox PH model
I'm curious about interpreting the coefficients of dummy variables within a Cox Proportional Hazards (PH) model. Consider a scenario where I have a sample comprising both male and female patients, and ...
- 363
1
vote
1
answer
65
views
Cox Regression: handling a time interval of drug administration when only given once
I would like to investigate the effect of a drug on survival with Cox regression. The drug can be administered either once or twice. In the univariate Cox regression, I see that a shorter time ...
1
vote
1
answer
315
views
In SAS what is the difference of including treatment variable in model and using the strata statement for treatment variable?
Im building a Cox Regression in SAS. My code looks like this:
...
- 77
1
vote
1
answer
28
views
Cox-model with exploratory variable measured after start study
I'm working with an unusual dataset, where some of the covariates/characteristics are measured after the start of the study (though without a timestamp!).
Basically, it's a dataset about an auction. ...
- 363
0
votes
1
answer
71
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Trying to understand utility of Cox vs. logistic regression
I am refreshing myself on the different types of regression models and am getting a little stuck between logistic regression and Cox regression/survival analysis. Here's an example: Let's say you are ...
- 3
0
votes
0
answers
25
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Survival Analysis where part of population never experiences event [duplicate]
We aim to examine the time it takes for a certain event to happen between two different groups of people in our sample. We are thinking of using survival analysis methods for this purpose.
The thing I ...
- 363
1
vote
1
answer
299
views
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
2
votes
0
answers
226
views
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
1
vote
1
answer
519
views
Using multiple genes building gene signature and survival analysis
This is the paper which is kind of I'm trying to implement based on my set of genes which i have narrowed down from WGCNA analysis.
Its a both conceptual and R related question[How to do it in R] my ...
- 235
2
votes
1
answer
617
views
Residuals pattern in Cox proportional hazards model
I do a survival regression on some time-to-event data (vehicle breakdowns) with some covariates (essentially the age of the vehicle and some boolean variables for vehicle type). I must admit that I am ...
- 621
1
vote
1
answer
950
views
Presenting spline terms from a Cox model
In the Survival vignette entitled "Spline terms in a Cox model"
https://cran.r-project.org/web/packages/survival/vignettes/splines.pdf
on page 3 there is this graph:
The plot is showing the ...
- 923
0
votes
1
answer
79
views
time to first medication switch as time-dependent covariate in Cox model
I need help with setting up my dataset to perform survival analysis with a time-dependent covariate. I read the Therneau et al. paper but I'm still unsure of how to set up the counting process format ...
- 173
2
votes
1
answer
446
views
Latent Class Analysis - Interpretation and integration with survival analysis?
I am approaching to Latent Class Analysis to identify "classes" of patients based on some variables.
Question 1: diagnostics of the results. I already gone through the discussion on whether ...
- 706
5
votes
1
answer
2k
views
Time to event = 0 in survival analysis?
In survival analysis, is it appropriate to have a time to event value of zero for a subject(s). For example, the subject experiences the event on the same date as their date of entry. Does this cause ...
- 923
0
votes
1
answer
20
views
Coding Survival Time: How to handle if a subject dies before your outcome (heart failure, HF) AND they have a HF event =1? [closed]
I am running a cox-regression model and am struggling with how to define my survival time to event (heart failure) if their time to HF (=1) AFTER they have died? i.e. it is documented they have a case ...
3
votes
1
answer
4k
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Cox model vs. Fine-Gray: hazard ratios & predicted cumulative incidence under competing risks
I am unclear about deriving both hazard ratios and a predicted cumulative incidence curves under competing risks. After reading this interesting article:
https://statisticalhorizons.com/for-causal-...
- 923
2
votes
1
answer
89
views
When developing models for effect estimation, is it advisable to perform internal validation and calibration using resampling methods? #rms
In predictive modelling, it is useful to perform resampling methods to assess performance e.g. validate() and calibrate() in the rms package in R. Is it useful / advisable to perform such methods when ...
- 923
1
vote
1
answer
1k
views
Can we compute predicted cumulative incidence after fitting a Cox model?
After fitting a Cox regression, we can compute the predicted survival curve S(t) e.g.
in R:
survfit(formula, newdata, ...)
where formula is a coxph object.
With the KM estimate, cumulative incidence ...
- 923
1
vote
1
answer
124
views
In the Cox model, how is modelling the hazard equivalent to modelling time to event?
In the Cox model, the dependant variable is often stated as time to event, e.g.
https://www.statsdirect.com/help/survival_analysis/cox_regression.htm
even though in the regression formula we model the ...
- 923
1
vote
1
answer
38
views
How to handle count type features in survival regression?
I want to understand how to model 'count' or 'customer behaviour' type features in survival analysis.
For example, assume that Netflix wants to predict time to churn after a customer upgrades to a ...
- 23
1
vote
1
answer
198
views
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
0
votes
1
answer
467
views
Anova with stratified Cox model
I'd like to use anova to investigate which variables are important to my Cox model outcome.
I tried using anova from ...
- 409
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
views
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
1
vote
0
answers
56
views
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
0
votes
1
answer
1k
views
Visualization after restricted cubic splines in Cox
I've used pspline to add restricted cubic splines to certain continuous covariates that violated the PH assumption upon first analysis. I identified these covarites ...
- 409
0
votes
1
answer
349
views
Cox time-varying coefficient memory allocation issue
I'm trying to add time-varying coefficients using the tt() function with coxph to solve the problem of PH violations in my Cox ...
- 409
1
vote
1
answer
383
views
Hazard ratio from Royston-Parmar model (flexsurv::flexsurvspline)
I have a covariate with time-varying coefficient with two categories (lets call it T), which I have modeled using the Royston-Parmar model from flexsurv package as following.
...
- 397
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
1
vote
1
answer
390
views
lifelines.CoxPHFitter - how are the p-values calculated? [duplicate]
I assume that lifelines.CoxPHFitter is using a Likelihood-ratio test (or is it using Wald?) to calculate p-values when testing for significance. But I have to be sure: is there an official source ...
- 11
2
votes
1
answer
411
views
Hazard ratio with time-varying covariates
I am confused about time-varying covariates in Cox models. I believe this refers to the fact that in the normal situation, you can calculate a hazard ratio for $X$, assuming $X$ for an individual is ...
- 555
2
votes
1
answer
183
views
Cox Proportional Hazards : Why not "Cox Proportional Survival"?
Recently, I thought of the following question: We are often taught about a "Cox Proportional Hazards Model" - this is able to model the hazard between different cohorts of patients, assuming ...
0
votes
1
answer
416
views
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
2
votes
1
answer
224
views
When computing period-specific hazard ratio using Cox, should I add variable:strata or full variable * strata?
Let's asusme I want to calculate separate hazards ratio in two periods, split like below.
...
- 23
3
votes
1
answer
309
views
Difference between CoxPH and logistic regression; data preparation for each model
I'm working on a research project of which the objective is to predict the customer churn probability in the next month. We have a dataset of monthly records for each customer with variables including ...
- 133
1
vote
0
answers
49
views
IPTW and adjustment in Cox Regression Analysis [duplicate]
A question on how to deal with inverse probability of treatment weighted-Cox regression analysis.
Basically, I am evaluating how to use IPTW in the context of survival (and specifically, Cox ...
- 706
1
vote
1
answer
552
views
In data setup for Cox regression, how to handle a subject's time before treatment of interest (i.e. before time-zero)?
Background
I'm designing a study that models time-to-event for two groups of study subject: people who receive a treatment and those who do not. I'm fairly new to applied survival analysis, so I've ...
- 739
3
votes
2
answers
697
views
Could Survival Analysis Tells the Probability of Death of Any Individual in Specific Time?
I am quite new to Survival Analysis and has only practiced with python package scikit-survival by its user guide.
I was actually confused by the output of cox ph ...
- 41
3
votes
2
answers
3k
views
Difference in stratification, interaction and subsetting Cox Survival Regression
I'm struggling to understand the actual differences in these three approaches that came to my mind.
The problem is: I want to analyze the impact of age on mortality in my cohort. However, I want to ...
- 706
0
votes
1
answer
658
views
How do you interpret outputs of Cox regression based on data type of an independent categorical variable?
I have the following data frame which consists of a grouping variable, as well as time ans status variables for survival analysis:
...
- 199
2
votes
1
answer
285
views
Cox proportional hazard Model $R^2 = 1$, good calibration - but Somers' $D = 0.16$
I have analyzed the survival time of a currency Unit "not being recovered" (for a debt) by fitting a Cox P. regression model.
Apparent $R^2=1$ is high, $D_{xy}=0.16$ . After bootstrap ...
- 1,035
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