Questions tagged [cox-model]
Cox proportional hazards regression is a semi-parametric method for survival analysis. No distributional form needs to be assumed, only that the effect of one-unit increase in a covariate is a constant multiple.
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Retrospective survival analysis censoring
I'm doing a retrospective survival analysis where I evaluate the recurrence of disease after surgery. The problem is that some of the patients don't come again to the clinic after surgery to do the ...
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Testing the proportional hazards assumption with a time varying covariate
One of the cohort studies I have carried out recently involved examining the association between post-diagnostic beta-blocker use and breast cancer outcomes in a cohort of breast cancer patients. ...
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Inverse sampling weights in Cox proportional hazard leads to violation of the PH-assumption? [closed]
I'm running a cause-specific Cox proportional hazard model to identify the association between potential risk factors and an outcome in a cohort study.
I am incorporating time-varying covariates, use ...
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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 ...
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Time-varying cox survival analysis with unknown age
I'm using coyote telemetry data to understand the impacts of various environmental characteristics on their survival. The data I have includes the locations of a few hundred animals throughout their ...
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Comparison of Kaplan-Meier and Cox models for survival analysis
I am looking at the results for survival analysis for leukaemia patients, categorised based on Copy Number Variation (CNV) levels using array comparative genomic hybridisation. So far I have plotted ...
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violation of cox proportional hazard assumption
I'm using cox regression to analyse my data. The explanatory variable is a congenital disease (X) and the outcome is an another disease (Y), which is a comorbidity of the congenital disease. I'm ...
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Predictions after Cox regression
I'm new to survival analysis and will apperciate your help regarding predictions after Cox regression.
I'm running a cox model (using stata's -stcox-) in which I examine the effect of a continuous ...
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Causal survival analysis in a large prospective cohort when treating incident events as the exposure
I'm currently working on a large prospective cohort with the basic demographic characteristics and various socioeconomic factors collected at baseline. This cohort was follow up since baseline entry ...
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Do I need to care if an adjustment variable violates the proportional hazards assumption?
I'm assessing the effect of an exposure variable on cancer risk. I am not necessarily trying to build the model that best predicts cancer risk, I am instead trying to best isolate the effect on cancer ...
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Can it Work to Run PCA only on a Subset of Highly Correlated Predictors prior to Regularization? (Cox)
I'm running Cox-LASSO (using glmnet as explained by Tay et al) on about 50 variables with about 300 observations. The variables fit into different categories like &...
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Results different using specific years for survival analysis vs zero time starting point
I am using survival analysis to model Treaty ratification, using country-treaty dyads as my primary unit. This means that I have several hundred survival spells covering different time periods (when ...
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Survival analysis sample size considerations
In statistical modelling, it is advised to have at least 10 observations per predictor as a rule of thumb. It is further suggested that in survival analysis this corresponds to number of uncensored ...
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Cox ph model with icenReg: how to code data without event indicator
I want to analyze my data with the interval-censored cox regression of the icenReg package.
I have 5 time-points (1,2,3,4,5). Events can only happen once. Each person starts with baseline (T1). People ...
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How to interpret Schoenfeld residual
Hi all,
Could you please help me to interpret Schoenfeld residual below.
Of note, I have very few outcome in one arm (Only 6 events and around 60 in the other)
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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:
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Cox Regression used for business churn/ lifetime value
Cox regression seems useful as a broad strokes model for measuring survival/ churn of a subscription-based product/ account lifetime estimate -- and the broad factors that might influence the survival ...
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Change Points in Cox Model
I have trained a Cox model on my dataset, which comprises patients entering the study at various time points. I suspect there might be multiple change points indicating shifting effects over time. My ...
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Cox model with two time varying independent variables for two legal reforms
I want to perform a proportional hazards model to study if job contracts were affected and became shorter/dismissal was more likely to happen after two labour reforms took place.
I understand that the ...
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Survival Analysis: adjusting the Kaplan-Meier curve and optimal sample size?
Following the tutorial https://www.youtube.com/watch?v=ujIMPpl2Tr0 from Stanford university, if the log-rank test (a popular test of Kaplan-Meier curves) does not contain report a statistically ...
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Churn/ survival prediction - Cox Regression and Recursive Factors
I'm trying to come up with a straightforward subscription churn (survival) model and - in broad strokes - see the most important factors by size.
I know this can be a loaded topic.
It looks like doing ...
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Modelling Incidents in Survival Analysis
I'm working with a mixture cure model in a panel dataset covering multiple products across several years. The time-to-event, defined as the duration between the auction start and product sale, is ...
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How to realise and interprete the interaction term in Cox regression model like this?
There are two covariates: smoking history(yes or no) and gender(male or female), and the outcome is OA. The author of a paper constructed a Cox regression model with an outcome including this: smoking ...
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Differences among Cox regression, accelerated failure time regression and linear regression when using no censoring data
I would like to investigate whether social economic status (SES) would be associated with the age of onset of mental illness, after controlling some possible confounders, in the cohort of patients ...
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Interpretation of interaction term in Cox regression
I am trying in Stata to analyze the effect of an exposure on the risk of an event, and to determine whether this risk increases or not after a temporal cut-off.
I have two groups of subjects, with ...
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Hazard ratios - one unit increase for a continuous variable measuring diversity (Blau index/ coefficient of variation), how to interpret?
I am having difficulty understanding how to interpret a one-unit increase/decrease for continuous variables in a Cox model.
Specifically, I have created the variables gender, age & nationality ...
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Survival analysis large number of small batches
I have a group of >10,000 right-censored survival cases, composed of a large number of small batches, with 1 to 7 cases in each batch. Failure rate overall is low, with 95% survival at maximum ...
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Model Selection on Coxme
I am building a "time to event" model using the coxme package in R. I have a lot of mixed effects (15) that I want to input into a global model and find the best fit for - is there a model ...
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Validity of using non-time variable in survival analysis
I’ve conducted a time-to-event analysis (accelerated failure time) for a research project, looking at the effect of an intervention on the probability of needing a blood transfusion during surgery. ...
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How do I test the Cox proportional hazards assumption if my model already has an interaction term?
If my model already has an interaction term (ex. sexHispanic ethnicity), how do I test the Cox proportional hazards assumption using interaction with time-dependent covariates? Would I enter timesex ...
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Cox model with ridge term: how to choose value of theta?
The coxph() function in R package "survival" is used to fit the Cox proportional hazards model. This function allows a ridge() term in the formula to penalise selected terms, which requires ...
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Calculate the risk probability with coefficients derived from Cox regression
I am new to survival analysis and I was wondering whether you could, similar to the logistic regression, calculate the intercept and the risk probability with the coefficients you acquire from the cox ...
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What is the predicted "risk score" generated by sjPlot plot_model?
I ran the following time-varying covariate cox model:
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Counting process style survival analysis - do I still need to interact with time?
I'm working in Stata with a Cox model and I have a dataset in counting process style (multiple records per subject).
Each observation per subject has covariants that could potentially be different ...
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Coefficient of one independent variable in Cox regression flips when inserting two other independet variables together
I'm running a cox regression to test the effect of different variables on crime.
There's one independent variable of interest (X), for which I hypothesize a negative relationship with crime (i.e., HR&...
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Can I compare predictive accuracy/best performing predictor using C-statistic and Integrated AUC in Cox model?
I have 2 surrogate indices, and 2 individual markers that were used to compute these indices. I also have demographic variables age, sex, education, smoking, drinking and exercise. The surrogate ...
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Survival analysis if one group is all censored?
I'm analyzing 2 groups where all of the subjects in one group are still alive, i.e. one group is entirely right-censored. The other group is a mix of censored and uncensored. Is a Cox proportional ...
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How does length of follow-up affect hazard ratio (prop hazards vs non-prop hazards)
As the title says, I'm trying to figure out how the length of follow-up affects the value of the hazard ratio (e.g. from a Cox model). If proportional hazard holds, then presumably the hazard ratio ...
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Proportional hazard assumption: graphical approach vs subsampling
Hopefully someone can guide me on the following.
I have a large dataset (> 151k firms with multiple observations per firm).
My dataset looks at firm failure using counting process style and my ...
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Bias in survival analysis: nice summary of all the different types and remedies
I am quite new to the field of survival analysis and am getting lost and confused with all the different types of bias that can occur, particularly in observational studies. For example, it appears ...
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Cox proportional hazard assumption, different results, which to follow
I was wondering if anyone would be able to help me understand whether the proportional hazard assumption is met or not.
For context I have a large dataset with >10 million observations (up to 40 ...
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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. ...
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Why is my Cox-regression bootstrapped p-value so different from the statistically derived p-value?
It's been years since I've looked at this or the R language, so I'd appreciate some help and simple explanations (I'm not a statistician).
Using bootstrap analysis, I'm trying to derive the p-value of ...
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Why such a large difference between Odds Ratios and Hazard Ratios?
I am studying the risk of dementia secondary to hearing loss. I have fashioned a Cox time-dependent model with multiple covariates, all with factor levels, but have also done a logistic model for ...
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Confounding by indication in observational cohort study: how to address?
Background
We are conducting a register based cohort study into effect of pain killer medication in cancer patients. Index date is date of diagnosis of early cancer in a defined study population. We ...
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Cox regression with binary time-varying covariate
I am researching the association between menopause and the incidence of diabetes(outcome).
I have a baseline and three follow-up assessments. Given that women transition from non-menopausal to ...
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Test assumptions Log-Logistic AFT Model
I'm considering adopting a Log-logistic Accelerated Failure Time (AFT) model for my analysis. Initially, I contemplated using the Cox Proportional Hazards (PH) model; however, the PH assumption was ...
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Power analysis for cox-ph model for 8 (correlated) groups?
I am investigating covariate X for 8 cancer types which all have different survival rates and will possibly show different impacts of other covariates like age, sex etc. Therefore I will run 8 ...
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Difference between left censoring and interval censoring
I'm dealing with some medical data which is made up of all admissions to hospital in a certain area, where each row is one patient admission alongside the various tests and demographic data done. Also ...
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Survival function estimate for coxph
I am currently wondering which estimator for the survival function is used for coxph objects from the survival package.
It is clear, that $\hat{S}(t|x) = \hat{S}_0(t)^{\text{exp}(\hat{\beta}^Tx)}$, ...
