All Questions
27 questions
0
votes
1
answer
33
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Setting a reference in Cox regression with splines and interaction
I run a Cox regression with a continuous variable age and a categorical variable sex. The model includes splines for the continuous variable and an interaction between both. I want to choose the ...
- 59.5k
0
votes
1
answer
317
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Cox survival PH violated variable is part of an interaction
One of my main predictors violates the PH assumption. I've been reading different ways to deal with this for a while and have decided on an interaction with time after making a person-period file (...
CommunityBot
- 1
2
votes
1
answer
42
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How to interpret interaction effects in a cox regression?
How would I interpret and report the highlighted boxes?
The variables:
Injury (0=uninjured, 1=injured)
Sex (0=male, 1=female)
Diet(1=10%EA, 2=50%EA, 3=100%EA, 4=150%EA, 5=200%EA)
(note: the “event” is ...
- 128k
0
votes
1
answer
112
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Cox regression with two-way interaction and interaction p value
Hi I am using Cox regression to do some survival analysis.
I have one continous predictor variable called "biomarker" and two binary categorical variables sex and diabetes.
I want to get the ...
- 51
4
votes
1
answer
413
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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. ...
- 102k
3
votes
2
answers
3k
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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 ...
1
vote
1
answer
42
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Interpreting interactions in Cox Proportional Hazard models
I am currently doing an interactions paper with cox models to assess time to criminal recidivism as an outcome, but am struggling with the interpretations.
My two variables that are part of the ...
- 128k
1
vote
1
answer
159
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How do I interpret the interaction coefficients in a cox proportional hazards model with two factors?
I am trying to look at how two different factors A (levels A1, A2, A3, A4) and B (levels B1 and B2), as well as the interaction between the two, influence the time to an event X. As a result I am ...
- 102k
1
vote
1
answer
167
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Is it possible to do a simple slopes analysis for a cox regression model (assuming the presence of a significant interaction)?
I have a paper in revision, in which I present a cox regression model with a significant interaction. The reviewer requests simple slopes. I am familiar with simple slopes from regular linear ...
- 102k
1
vote
1
answer
190
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Survival analysis interaction interpretation: interaction is insignificant, but pairwise comparison does hold significance
I'm new with survival analyses, and have been breaking my head over this for a while, so I hope someone can explain this in a simple manner:
Variable
HR
Gender(Female)
1.391*
Treat (Yes)
0.544***
...
- 102k
2
votes
2
answers
1k
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Which method of handling non-proportional hazards (here: crossed KM curves in 2+ points) would you prefer?
I have an experiment, where I compare two groups over time in frames of the time to event analysis.
The Kaplan-Meier curves cross 3 times.
It means, that the hazards ratios switch to the opposite side ...
CommunityBot
- 1
0
votes
1
answer
717
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About getting baseline survival probability for a piecewise Cox model with interaction term
I use Cox regression model to develop a risk prediction model for a disease and want to get a risk equation from this. The codes for that below is something like below
...
- 102k
1
vote
1
answer
1k
views
Cox regression in subgroups
I ran an analysis in which I used Cox regression to investigate the relationship between a number of predictor variables and time to death. I used R for that: ...
- 1
1
vote
1
answer
1k
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How to get confidence intervals for ALL cases of an interaction in the Cox model? (ideally with R)
My question is illustrated with the output of R, but the rule should be software-agnostic.
Let's assume I have this exemplary output of the coxph result in R:
...
CommunityBot
- 1
1
vote
1
answer
436
views
Covariate and Interaction Not Significant When Both in the Model
I am looking at a survival model based on dosing variables, all of which are continuous. I have noticed when categorized, based on Kaplan Meier Curves, that low, medium, high doses behave differently, ...
- 79
1
vote
1
answer
106
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If we say "Survival difference adjusted for covariates" do we mean just additive adjustment, or allow also the interactions?
Let's make it independent from any statistical package, so I will provide just numbers for the illustration. Maybe this give you some clues.
I want to compare two survival curves, for group A and B.
...
- 102k
0
votes
0
answers
33
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Statistical design: retrospective analysis of effectiveness of medication
I have a retrospective dataset that has records of the medications a patient was administered to prevent recurrence of heart attack. The goal is to determine if a particular drug or combination of ...
- 82.8k
1
vote
1
answer
771
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Interaction not significant in Cox regression model?
I ran a cox model with an interaction between two categorical variables (sex and treatment group) included like:
...
CommunityBot
- 1
0
votes
0
answers
107
views
Interpreting a hazard ratio for time-dependent coefficients
I have a cox model with two main effects (x,y) and two interaction terms (xt, yt) where t is time. I am having some trouble interpreting the hazard ratios. Does the hazard ration become more of an ...
- 113
2
votes
1
answer
3k
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Violation of proportional hazard for covariate but not for interaction it's part of in a Cox Proportional Hazards model
I have a problem in which one of the covariates in my model violates the assumption of proportional hazards, but the interaction it is part of does not.
Data info:
Lifespan - mosquito time to death (...
CommunityBot
- 1
2
votes
1
answer
9k
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How to create a covariate × time interaction term in Cox regression? [duplicate]
In Cox regression, it is sometimes inevitable that the strength of a predictor will vary across time (Singer & Willett). This violates the proportionality assumption, but can be incorporated in ...
CommunityBot
- 1
6
votes
1
answer
12k
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Interpreting interaction terms in Cox Proportional Hazard model
I am new to survival analysis, so forgive me if this questions is stupid - but I couldn't find the answer anywhere else. We are looking at readmission to a treatment program, which is defined as ...
- 2,172
5
votes
1
answer
25k
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Interaction effects in Cox model (continuous, dichotomous, and categorical variables)
I get a couple of puzzling results in my (repeated event) cox model when I introduce interaction effects. I will here pose several questions about interaction effects (in survival analysis context) in ...
CommunityBot
- 1
2
votes
1
answer
108
views
R adds unexpected variable to interaction model
Not sure if this is more of a programming question (in which case please move to stack overflow) or a statistical model question (in which case, please read on!)
I'm exploring a data set and doing ...
- 141k
8
votes
1
answer
1k
views
Violation Proportionality Cox model - Repeat analysis?
I'm new to survival analysis, but I've been reading some papers and books and I got a nice model.
However, one of the variables (Sit) does not met the proportionality assumption for the Cox model. ...
- 2,429
2
votes
1
answer
1k
views
Interaction in Survival analysis
I am a physician and clearly not a statistician (I try to understand why and how to perform the right analysis, but I don't understand the formulas). I am using SPSS v.19 in analyzing my data.
I try ...
- 128k
0
votes
2
answers
5k
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Interaction terms in Cox PH model
I am wondering if there is a way to interpret an interaction term from the coefficients rather than just looking at the survival curves?
The factors involved are A, B, and C, which are all binary ...
- 59.5k