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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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 ...
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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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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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Equivalence between Mundlak and FE estimator: what with the generalized residuals of the control function?
I want to model the effect of an endogenous (left-censored) explanatory variable on a continuous outcome variable using an unbalanced panel dataset. For this, I use a control function approach.
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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 ...
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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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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 ...
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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 ...
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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 ...
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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, ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 (...
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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 ...
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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 ...
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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 ...
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What are the advantages of using Functional Data Analysis (FDA) over traditional Time Series or Stochastic Process approaches?
In the case where the curves (functions) are defined on a time interval.
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Ways to include time in hierarchical mixed effects model
My colleagues and I have been using a hierarchical mixed model that so far has provided good predictions. As time goes on, however, it's clear that not including time as a factor in the model degrades ...
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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/...
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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 ...
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How to specify a regression model with a time-varying predictor and time-varying outcome?
I'm trying to specify a regression model. The data spans 6 time periods in a patient population. Periods 1-3 are blood glucose samples, and 4-6 are troponin samples (cardiac damage marker). So, a ...
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In a hierarchical longitudinal model, is it possible to define a time-varying covariate on its own time frame, nested into the top-level time frame?
I've got time-varying predictor sampling events nested under each outcome sampling event (also sampled at multiple time points). So, I've got time structure at level-1 (outcomes), but also at level-2 (...
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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....
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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 ...
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GLMM on temporally correlated count data from a designed agricultural experiment
I have carried out a designed agricultural experiment with two treatments and recorded the effect on the abundance of a pest insect on three dates. The field experiment was divided into four blocks ...
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Problems with using average of time-varying variable as a level 2 predictor in growth curve modeling?
I am running a multilevel growth curve model predicting trajectories with observations over time nested within people. I am specifically interested in if amount of exposure to an event explains/...
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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 ...
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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 ...
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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 (...
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Is it possible to complete a Time-Lagged Multilevel Model with time-variant predictors that change systematically with time?
I have a data set of 139 individuals who provided responses to a series of questionnaires at 5 times points (0, 3, 6, 12 and 18 months) across treatment. Time is included as a covariate in the model (...
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Time series with categorical response variable
I have a question about modelling but I don't even know what kind of model to start looking into.
I have panel data with multiple waves. The response variable I'm interested in is categorical variable ...
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Accounting for study entry date in logistic regression for generating propensity scores
I am analyzing 30-day mortality associated with two treatments. I am planning to use IPTW. I would like to account for time in my propensity scores. The study inclusion dates span 15 years, so I would ...
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Cox model: how to model treatment variable when timing is unknown
We have cancer medical registry data, including information on date of diagnosis, treatment, and followup e.g. date of death etc. However, we only know type of treatment received for each person. We ...
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Which method to use to scale/mean center a time-varying covariate in latent growth models (SEM)?
I have longitudinal data across several time points. At each time point, participants completed an online test up to 3 times (i.e., measurements were completed 1-3 times at each timepoint). The number ...
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How to compare groups when one treatment group has no events and the treatment variable is time varying - survival analysis
I am comparing two treatment groups and I have 3 different types of outcomes. The dependent variable, treatment, is time dependent and so I conducted time dependent cox regression for each of the ...
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Sample Size Estimation for Two Sample T-Test with Fixed Sample Size and Time-Varying Covariates
Let's propose we have a set of n heterogeneous study participants that independently from one another accrue salaries over time. We now want to evaluate a treatment to the study participants that is ...
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Latent growth curve models (SEM): determining the shape of curve with unconditional time-varying covariates
I have a question about determining the shape of a curve (linear vs. quadratic) in latent growth curve models within a structural equation model framework.
If you are including time-varying covariates ...
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longitudinal data with time-varying binary exposure in linear mixed model
Good morning, i am looking for some help with longitudinal data with time-varying binary exposure in linear mixed model. Outcome is continuous variable. I am going to use R and the lme4 package. I ...
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Cox analysis with a variable exposition with two measures at different times
I measured blood glucose for a sample of 500 participants at baseline and one year after. My issue is death.
I already did a Cox survival analysis for the first blood glucose with my 500 ...
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Numerical rank deficiency in P-spline based varying coefficient model
I am studying the following varying coefficient model from [1]:
$$
d_x(x,y) = s_x(y)x + c_x(y) + o_x(x)
$$
$$
d_y(x,y) = s_y(y)x + c_y(y) + o_y(x)
$$
where $x$ and $y$ are covariates, $d_x$ and $d_y$...
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Time-varying variables in Cox regression- can I fix them?
I have a clinical dataset with variables measured over a number of years at various assessment time points. This data was not intended for research initially which is why there are some challenges.
...
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cox regression time-varying effects (variable exposure as a continous variable)
Is it possible to do Cox survival analysis with time-dependent covariates, but include the exposure variable as a continuous variable?
I have an exposure measured at two different times, and my ...
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Cox model: advice on constructing time varying exposure to drugs
I am performing a survival analysis on medical registry data and would like to model drug exposure to estimate a continuous dose-response curve. I have drug data like this:
where ATC is the unqiue ...
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R survival: time dependent coefficient for time dependent covariate
I am doing a survival analysis where I have a time dependent covariate cov. I have included the time dependent covariate with the ...
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Why am I getting such different hazard ratios from the Andersen-Gill model compared with the Prentice-Williams-Peterson model?
I am trying to model recurrent composite events to compare differences in recurrent events between two therapy groups. I have completed time to first event Cox regression as well as recurrent event ...
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Can I assess proportional hazard assumption by Schoenfeld's method in the time-dependent Cox model with restricted cubic spline?
I am considering a survival time analysis with death as the outcome. I first performed a time-dependent Cox regression with BMI as the independent variable (linear model). The likelihood ratio test ...
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hierarchical regression for repeated measures
I did a study to see if an app would reduce anxiety over time. I allocated my patients into 3 different groups, those that received standard care, those that received app version 1, and those that ...
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Dealing With Immortal Time Bias in Observational Studies
I have an observational cohort of patients with underlying pulmonary disease. The cohort is derived from multiple centers across the USA. My scientific question is whether or not there is an effect of ...
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