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Questions tagged [time-varying-covariate]

A variable that records something about a study unit in a longitudinal study that changes over the course of the study.

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Is "relative risk time" meaningful? (transient relative risk)

Context: I'm trying to specify a data-generating / mechanistic model for a simulation study. I assume that exposure $e$ (a short event) has a transient effect on the relative rate of another process $...
jessexknight's user avatar
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Modeling Condition Specific Associations

I am trying to model a crossover repeated measures design in which individuals complete both the active and control conditions. These individuals also complete cognitive testing before and after both ...
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Time-varying coefficients based on binary variables

I am doing a survival analysis, and for each individual i have one event occuring (the one of interest), then i have baseline events (inc1 & ...
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Survival analysis - any benefit to splitting on failure time instead of covariate change for creating time-varying covariates?

When needing to create a time-varying covariate for a survival model, I am accustomed to using (what I understand to be) a counting process structure for my data, where each individual may have ...
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A prospective longitudinal study with time dependent covariate

My question is similar to Sample size calculation for multivariable Cox regression for treatment comparison. I have a prospective longitudinal study over three years. The purpose of the study is to ...
user413503's user avatar
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Longitudinal analysis

I have a question. Suppose that I want to analyze if a particular variable "X" affects the incidence of a disease "D," but I do not have the information about "D" at the ...
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How to deal with exposure status change and outcome contribution in different exposure status?

I want to estimate the risk of cardiovascular events in patients with diabetes (exposed group) compared to patients without diabetes (unexposed group). How do we deal (in the analysis) with patients ...
Nao's user avatar
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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 ...
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Interpretation of coefficient for binomial longitudinal outcome in joint models / modeling

When performing joint models of survival and longitudinal outcome, how do we interpret the coefficient when the longitudinal outcome is binomial? In the slides here pp. 131 to 142 https://www....
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how to distinguish negative shock or positive shock in TGARCH model?

IN the picture, how to know whether the yellow highlighted part exists or not? because the return of day 1000 drop from 0.02 to 0.01, so there was a negative shock, so l should keep the yellow ...
kinsley's user avatar
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Bayesian time varying coefficient

While I am writing a thesis on how the cyclicality of fiscal policy evolves over time in certain countries using Bayesian time-varying regression, there are some questions that I would like to ask. I ...
Yohan's user avatar
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Paired t-test or ANCOVA or linear mixed model?

Recently I encountered a situation where each subject has a continuous response variable at 3 time points ($t_0$, $t_1$, $t_2$). There are $3$ treatment groups ($A,B,C$), and some covariates. Consider ...
Ronald Carlos's user avatar
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Interpretation of the Hazard Ratios in Lifeline's Time varying cox regression

I'm trying to understand how to interpret the hazard ratio of time-varying covariates, returned by lifelines.CoxTimeVaryingFitter. Following the example on their page, I have the following data: ...
asere's user avatar
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Time varying covariates in dif in dif

I'm working on a dynamic Difference-in-Differences (DID) analysis to assess the impact of child care leave on individuals' wages over their working life. My database includes information on the date ...
Andres Jimenez's user avatar
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pseudo-values for time-variant covariates

I have the following time-varying survival data: ID Start Stop Group Z event 1 0 8 1 0 false 2 0 5 0 0 false 2 5 8 0 1 true 3 0 3 1 0 false 3 3 12 1 1 true I want to calculate the Jackknife ...
Stiven Choking's user avatar
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Bad model fit for a second-order growth curve with time-varying covariates. Do I have to find a way out or will it depend on the aim of the analysis?

I am running a second-order latent growth curve model with seven repeated measures. I have 2 time-invariant covariates (TIC, country and sex) and 2 time-varying covariates (TVC, both are latent ...
EmH's user avatar
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Estimating hazard ratios for values of a continuous predictor without catagorizing

I have a dataset where I am looking at time to diagnosis as a continuous predictor of mortality. Using a Cox model, I want to estimate HRs for values of this continuous predictor to be able to say ...
user405452's user avatar
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Should I use strata(), cluster() or frailty() to account for center specific characteristic in a time-varying analysis

The research question revolves around whether a time-varying intervention at a center enhances the transplantation hazard per person. I have patient-level data and I need to account for the center ...
Claudio Bravo's user avatar
1 vote
2 answers
58 views

Marginal structural model yielding different hazard ratios depending on time split

I am using a marginal structural modeling approach to adjust for time-dependent confounders, looking at the risk of developing disease. I have used tmerge in R to account for the time-dependent ...
Rich R's user avatar
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How to deal with exposure or outcome at time 0 in a time-varying Cox model

Let's say I have a dataset with a list of cars, some of which have self-driving function which is the time-varying exposure. Some of the cars had this function from the beginning (time 0) and some ...
Claudio Bravo's user avatar
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Interpreting a Schoenfeld plot for Cox PH univariate model and correcting for violation of PH assumption (R)

I am having trouble understanding how to interpret a Schoenfeld plot and how to correct for the violation of PH assumption in Cox PH model when using continuous numeric covariates. Here is the code I ...
Tyler Brown's user avatar
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Survival analysis with time-varying covariates observed only once

I am currently researching fish survival analysis. The weight and number of live fish were observed until the end of the rearing period, and the number, weight, and timing of dead fish during the ...
Jongwon Kim's user avatar
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Time varying-effect of smoking on BMI over time

I have a dataset with longitudinal measurements of BMI. The BMI for each participant is measured at 10 different time points. The aim of the study is to investigate how BMI evolves with time. Smoking ...
Sharon's user avatar
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4 votes
1 answer
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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. ...
Oliver's user avatar
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Unbiased estimation of treatment regime contrast with time-varying treatment and outcome

I have some troubles finding a strategy to identify the causal effect I am looking for from my observed data. I am assuming the following DAG: where $Z$ is the result of a coin toss (randomization), $...
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Simulating Time-Dependent Covariate and Applying coxph Function to Estimate Association Parameters

Let $T$ denote a failure time random variable drawn from a proportional hazards model with a time-invariant covariate $X\sim U(2, 7)$ and a time-varying covariate $Z(t) = kt$ for $k > 0$. Assuming ...
J McVittie's user avatar
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How do I incorporate a patient's current age into a survival model?

I have a dataset with 10,000 patients, and for each patient, I have the following information: Biological sex (male/female) Baseline age (age at the time the patient joined the study) Age at the ...
nxk056's user avatar
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1 answer
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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 ...
maile's user avatar
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1 answer
164 views

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 ...
Laura Hill's user avatar
3 votes
2 answers
205 views

Linear Mixed Models for randomized clinical trial

I am working on analyzing data from a randomized clinical trial which is studying the effect of a mesh type on patient-reported pain. The 2 study arms are the 2 different meshes (biologic and ...
S. Patel's user avatar
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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 ...
Laura Hill's user avatar
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76 views

Using both time dependent covariates and time dependent coefficients in a Cox Model

In the context of a study, I am comparing two surgical interventions and I am interested in the time delay before the occurrence of a specific clinical event after surgery. I have conducted a ...
Kant's user avatar
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19 views

How to test for effect modification and mediation by time-varying factors in a longitudinal context?

I have longitudinal data with measures of an exposure, outcome, variables that may be mediators or effect modifiers, and confounders at 3 time points. I would like to account for time-invariant and ...
JRB's user avatar
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Formatting cox data with time-dependent continuous variables and unequal time intervals

I am planning to do a joint model for longitudinal and survival data, with multiple time-dependent/time-varying continuous variables. However, I am having trouble re-formatting my dataset to be in a ...
Lily Vi's user avatar
2 votes
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139 views

Time varying coefficients with splines in Cox model

I am wondering whether it is valid to fit spline interactions between time and predictor variables (either categorical or continuous) in a Cox model. I am having difficulties specifying this model, ...
user167591's user avatar
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2 answers
43 views

Why can't we use normal Cox ph survival model by incorporating time-varying covariate features into it?

Using the stanford heart transplant dataset, I have seen articles on why time-varying covariates are important as an input for survival analysis models. But can't we incorporate the time at which ...
albin02t's user avatar
1 vote
1 answer
55 views

Cox survival model with pre-determined time-dependent covariate

I am working on the Cox survival analysis model with time-dependent covariate, which is a very very common model. However, in most papers and R packages, I noticed they estimate the parameters of ...
Ellen1230's user avatar
1 vote
1 answer
39 views

What survival model can handle a different time for each covariate?

I would like to fit something like a Cox model but each covariate on my data could have been measured at a different time, different for each person. Is there any alternative survival model allowing ...
skan's user avatar
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64 views

How to Conduct and Analyze Time Series Ordinal Logistic Regression using R?

I am working on a project where I have collected ordinal outcome data at three different time points. I am interested in modeling the change over time with these ordinal outcomes. Initially, I ...
Karl A's user avatar
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1 answer
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Latent growth curve model - can I talk about an effect over time if I only have my outcome at the last timepoint?

I have a latent growth curve model with two variables. X (exposure to media) was measured at 5 time points over several years. Y (misinformation proneness) was measured only at the last time point (...
Maria Medeiros's user avatar
1 vote
1 answer
110 views

Time-independent variables in survival analysis

In any non-cross-sectional, prospective (whether it be longitudinal, survival, etc) study there are baseline variables which contain the status of the variable at the beginning of the study, and these ...
LucaS's user avatar
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4 votes
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98 views

Time-Varying-Intercept in Logistic Regression

Background I have a panel of binary response data - I have a different cross section of individuals each month, across many months, and the outcome is 0 or 1. When fitting a logistic regression that ...
Adam Check's user avatar
0 votes
1 answer
445 views

Cox time varying covariates (time dependent)

I have a question about an extended cox regression model. I have reviewed several materials, such as "D.G. Kleinbaum and M.Klein, Survival Analysis: A Self-Learning Text, Third Edition" but ...
Levi M's user avatar
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1 answer
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repeated measures multinomial logit or competing risks?

I need some help/advice for tackling the following problem: interested in exploring the association between various covariates and the reason for termination from a data registry. The hypothesis/...
R. Simian's user avatar
1 vote
1 answer
133 views

Cox regression: are my covariates time-variant? what with PH assumption violation?

I was wondering if any have advice on what the correct steps/interpretation are with regards to the following questions on Cox regression. As a side note, I am using STATA MP 15.1 to analyse the data ...
Laura Hill's user avatar
0 votes
1 answer
340 views

Time Dependent Interaction Term in Cox Regression

I am running a cox regression for survival analysis using the coxph() function in R for a very large dataset. My model is set up as: Surv(time,event) ~ age + race + sex +... The study period is 1 year....
Matt's user avatar
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48 views

Do dynamic logistic models require data points to be temporally independent?

despite my searching, I cannot find a clear answer to the question: Do dynamic logistic regression models require data points to be temporally independent? An answer, an hint and/or a reference would ...
Jehol's user avatar
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5 votes
0 answers
43 views

Generalizing ATT to the time-varying setting

In the case of a point treatment, the average treatment effect among the treated (ATT) is the treatment effect standardized to the subset of the sample that received treatment $A=1$ as an estimate of ...
elbord77's user avatar
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0 votes
1 answer
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interpreting HR with time dependent covariates cox regression

I did time-dependent covariate analyses with cox regression in R. But I wonder if the interpretation is the same as for a cox model with a fixed covariate? Context: in my analysis the physical ...
lodp75's user avatar
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2 votes
1 answer
476 views

Cox Time Varying Regression model - python lifelines - start and stop variables

I have a question about the implementation of Cox Time Varying Regression model, that I need to perform to understand the impact of co-variates on my survival prediction. I found an example here (...
Valerio Pugliese's user avatar

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