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Results tagged with proportional-hazards
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user 28500
Proportional hazards is an assumption of the Cox proportional hazards model of survival analysis and some other models as well. The assumption is that a linear increase in the predictor will have a uniform multiplicative relationship with the hazard.
1
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hazard ratio interpretation
The best way to proceed is simply to state the result that you found: "The hazard ratio for Group A versus Group B in terms of survival is 0.56 (95% CI: 0.36 to 0.87)." As comments have suggested, you …
- 101k
1
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Why is cox.zph splitting terms?
The cox.zph() function* has a terms parameter setting. If that is set to TRUE, all levels of a categorical factor variable are considered together; if set to FALSE, you get separate analysis of each l …
- 101k
0
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Doing Cox univariate analyses followed by multivariable analysis on significant variables?
This type of approach is often used,* but it has some dangers. First are the problems inherent in any attempt at automated model selection like that. Second is the inherent omitted-variable bias in Co …
- 101k
2
votes
Accepted
How do you present results of a proprtional hazards model when the outcome is a good thing?
I think it would be simplest just to spell things out clearly in the axis labels, figure captions and text. Don't underestimate the intelligence of your audience. Just be very clear. I certainly agree …
- 101k
4
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Interpret hazard ratio that has huge value
Let's start with the main question, the interpretation of extremely high hazard ratios (HRs). As implicit in the comment from @Penguin_Knight, this is simply an issue of scales like, for example, in e …
- 101k
1
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Continuous Variable No Longer Follows PH Assumption When Categorized
There is a great introduction to the pitfalls of categorizing continuous variables on this page, with links to more information. It seems that you have a continuous predictor that was linearly related …
- 101k
5
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Cox Proportional Hazards: Why p < 0.1 in univariate to be included in the multivariate
Omitting any outcome-associated predictor from a Cox multiple-regression* model runs a risk of omitted-variable bias. Unlike the situation with ordinary least squares discussed in that linked Wikipedi …
- 101k
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About the interpretation of time-varying variables with time interaction in Cox-PH model
Strictly speaking, if the coefficient for any predictor violates proportional hazards (PH) then your model does not meet a critical assumption of Cox models. Quoting from Section 3.5 of the main R sur …
- 101k
10
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Extended Cox model and cox.zph
This question deserves a more up-to-date answer on a few accounts. First, the cox.zph() function has substantially changed with recent versions of the survival package, so there might be confusion wit …
- 101k
2
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How to interpret the schoenfeld residuals plot
The proportional hazards (PH) assumption might be OK, but the plot suggests that you need to think carefully about your model. You will have to use your knowledge of the subject matter to make your de …
- 101k
1
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Training on censored data with varying sequence length
In classical discrete-time survival analysis, the data are often broken down even farther, to individual data points for each time point within each sub-sequence (as you propose; indexed if you think …
- 101k
3
votes
Accepted
What is the meaning of "t" in Cox hazard proportional model?
To extend the answer from Aksakal a bit, note that there are two different uses of time in this analysis. One is the t (described by Aksakal and used in the cited equations) for time at which survival …
- 101k
1
vote
Accepted
Can I force the direction of hazards ratio?
Even if you could force a Cox regression hazard ratio in one direction or over a range, it would almost certainly be unwise. What you describe sounds like a common phenomenon in multiple regression, w …
- 101k
2
votes
Accepted
How does time specific hazard ratios relate to time dependent incident dynamic ROC AUC?
There are a few somewhat related but separate issues here.
First is the apparent violation of proportional hazards (PH). Although the test showed a "statistically significant" violation of PH, the plo …
- 101k
3
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How to cope with non-proportionality?
With about 6000 cases and 1200 events, the simplest way to proceed would be to stratify on subgroups of age. That would allow different baseline hazards for the different age subgroups, with the propo …
- 101k