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Questions tagged [frailty]

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1answer
19 views

random vs. stratified Cox model

What is the difference in interpretation of the effect estimates in a Cox model stratified by sex vs. with a random statement for sex? Thanks.
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0answers
14 views

Shared Frailty Assumptions

Do we need to check the proportional hazards assumption when running a shared frailty model for clustered data?
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0answers
46 views

Frailty or median values in my cox proportional hazards model?

I am analysing data of woodpecker-made holes and I am interested in seeing what covariates and to what degree affect the survival of these holes (otherwise known as cavities). However, I encounter the ...
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0answers
49 views

Cox model with frailty (partial loglikelihood and df)

I am fitting a Cox propotional hazard model with a frailty term using the survival package in R. When I remove a fixed efect, I ...
1
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1answer
493 views

Can someone explain the meaning of “shared frailty” in survival analysis

Can someone explain the meaning of "shared frailty" in survival analysis in layman english ? a concrete example of where one would use this would also be very helpfull. thx kindly Stig
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0answers
51 views

Responding to a reviewer: How to apply frailty to a Cox regression analysis in this situation

I am a medical doctor not a statistician. I have 60 patients who were assessed by 400 doctors (each doctor individually evaluated the clinical data on each patient). The doctor was then asked to say ...
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0answers
52 views

Comparison of longitudinal change in several parameters in same individuals: violations of survival analysis?

I am trying to compare 4 different (but correlated) parameters (biomarkers of a disease with continuous values) to identify which parameters would detect more deteriorating subjects and in a shorter ...
4
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1answer
225 views

Survival analysis for patients that have been subjected to multiple treatments

I have data for patients that were subjected to either one treatment or multiple treatments at various points in time and I need to analyse their survival times after treatments. This of course means ...
1
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1answer
798 views

Unobserved heterogeneity in Cox model

I have some questions about the Cox model and unobserved heterogeneity. I work on a sample of firms divided in two categories: cooperatives and corporations. I want to test the influence of some ...
1
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1answer
578 views

Software for survival regression with interval censoring and frailty

I'm conducting regression analysis on sleeping time data. The data is survey data and the answer possibilities are of type "less than 4 h", "5 h", "6 h", etc. so they can be thought to be interval ...
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0answers
379 views

How to plot splines in a coxph model that includes a frailty term?

I have a Cox PH model including a smoothing spline and a frailty term as follows: fit<-coxph(Surv(start,end,exit) ~ x + pspline(z) + frailty(a)) When I run a ...
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0answers
38 views

Determine number of excess events in survival analysis

I have run a survival analysis on two group of people that saw different ads during an ad campaign. I would like to calculate the number of excess events that occurred due to the exposure to the ad. ...
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2answers
5k views

Precisely how does R's coxph() handle repeated measures?

Context I'm attempting to understand how R's coxph() accepts and handles repeated entries for subjects (or patient/customer if you prefer). Some call this Long format, others call it 'repeated ...
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2answers
220 views

Survival Analysis/Frailty Model

I am trying to build a probability model for the following situation: I have a very large dataset, whose rows are users and columns are the features. All the users visit a particular store X (once ...
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0answers
570 views

Survival analysis with Frailty on large dataset

I am trying to fit a survival analysis in R with non-recurrent events and time-varying coefficients. The baseline distribution is exponential or Weibull and the ...
1
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0answers
578 views

Model assumptions and diagnostics for proportional hazard regression model with frailty in R

I am wondering are there any assumptions that must be met in the proportional hazard regression model with frailty? I remember that in regular proportional hazard model without frailty all variables ...
0
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0answers
389 views

Result of the summary of the proportional hazard model with frailty in R

I am trying to fit coxph a model with frailty with syntax below: ...
9
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2answers
2k views

Should I bootstrap at the cluster level or the individual level?

I have a survival model with patients nested in hospitals that includes a random-effect for the hospitals. The random effect is gamma-distributed, and I am trying to report the 'relevance' of this ...
1
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1answer
483 views

Link function for log-logistic shared gamma frailty model

I've been asked to replicate a study that models an accelerated failure time survival model with a log-logistic distribution and gamma distributed frailty (a 'log-logistic shared gamma frailty model') ...
2
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1answer
1k views

Survival analysis in SAS-is there a way to include a random effect with interval censored data?

I'm trying to use some form of survival analysis (e.g. accelerated failure time or proportional hazards) to study seed germination time. My data is interval censored (also called "grouped-time") and ...
2
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0answers
883 views

How to interpret the frailty terms in a coxph.penal model?

I have the following coxph model: Surv(Y) ~ genotype + treatment + age + frailty(batch) + genotype:frailty(batch) ...
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0answers
150 views

Frailty model using bootstrap sampling

Let say I have a 'kidney catheter' data set which is built in survival package. Data are about the recurrence times to infection, at the point of insertion of the ...
2
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0answers
562 views

Proportional odds model with random effects

I have a survival data set. I want to see the cluster specific variation, which we usually can do by using Cox proportional hazard model with frailty. But, the constant hazard ratio assumption of Cox ...
0
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1answer
152 views

Estimate of parameter $\beta$

Suppose I've a set of information, ...
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0answers
820 views

Variance of a random effect in Cox PH

I want to fit a Cox PH model with random effect (Gamma frailty). Here is an example with 'kidney catheter' data set: ...
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1answer
2k views

EM algorithm R code on Cox PH model with frailty

Let say I have a 'kidney catheter' data set. Data are about the recurrence times to infection, at the point of insertion of the catheter, for kidney patients using portable dialysis equipment. ...
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1answer
2k views

How to generate predicted survivor curves from frailty models (using R coxph)?

I want to compute predicted survivor function for a Cox proportional hazards model with frailty terms [using survival package]. It appears that when frailty terms are in the model, the predicted ...
8
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1answer
7k views

Which model should I use for Cox proportional hazards with paired data?

I am hoping someone can help me with which model (frailty, strata or cluster) I should use for my data. I have paired data so I need to take that into account when modelling the Cox PH and am unsure ...
4
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2answers
194 views

How should I analyze data on birth intervals of women?

I have data on birth intervals of women. Birth interval refers to the time interval from one child's birth date until the next child's birth date. Here, dependent variable is the birth interval, ...
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1answer
1k views

Any ideas about how to analyze survival data with pseudo-replication (dependent data)?

I am a student, working with a team on a large-scale ecological experiment. We want to analyze survival data which has been derived from an experimental design with some pseudo-replication. This ...
3
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2answers
13k views

How to conduct conditional Cox regression for matched case-control study?

I am attempting to find a program that will let me conduct Cox regression on my matched case-control dataset. Please assist. p.s. I have STATA, SPSS, and MedCalc