# Questions tagged [survival]

Survival analysis models time to event data, typically time to death or failure time. Censored data are a common problem for survival analyses.

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### Trying to understand formula for the Survival Function (survival analysis)

I'm trying to learn the Cox Proportional Hazards Model on my own, and found this link that describes it in clear terms. But when I get to Formula (5) ($S(t) = \exp(−H(t))$) I can't figure out where ...
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### Can survival models be used for modeling progression along a sequence of events?

I am wondering whether survival analysis can be used to model situations where the subject progresses through stages. Here is an example of what I mean: Suppose I want to track the progress of ...
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### Determining sample size for proportional hazard

I am in the design phase for a longitudinal study examining the effect of a predictor (neighborhood risk score) on time to an outcome (re-arrest), as well as whether or not the variation explained by ...
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### Logrank test for trend (proportional hazards)

How one can create a logrank test for trend and does it differ from normal logrank test? Any suggestions or literature? Maybe some R examples and functions?
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### Inference with only left-censored data

Suppose I have a data set that is only left-censored data, ex: <5, <5, <5, <10, <10, <10 A technique to handle left-censored data is the Kaplan Meier estimate, see page 5 of this ...
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### Discrete Time Survival Analysis - Correct Way to Write Survival Function

I have seen several ways to write (and calculate and interpret) a survivor function in discrete time survival analysis and I wonder which is correct or if they both are, but the interpretation and/or ...
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### Understanding survival at time function

This question is related to a few others (Here,Here) on the topic as I have been searching for information. Hopefully this one is sufficient. 1) I am seeing differences in the relationship between ...
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### Left censoring with time-varying covariates

I have a data with some participants entering the study with a disease of interest already present. For others, I have several points of observation where different factors were measured (such as ...
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### Survival analysis when exact time to event unknown?

My dataset (example here) represents a long-term capture-mark-recapture study, approximately 20 years duration. I am interested in looking at how the survival of animals is influenced by their sex and ...
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### Interpretation of Weibull Accelerated Failure Time Model Output

In this case study I have to assume a baseline Weibull distribution, and I'm fitting an Accelerated Failure Time model, which will be interpreted by me later on regarding both hazard ratio and ...
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### Must the hazard function integrate to infinity?

Consider a non-negative random variable $T$ arising in the context of survival/reliability analysis (usually representing the time until some event occurs). It is well-known that the survival ...
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### Predict when a user logins next

I am building a user login prediction system. This is my first time building any prediction system. Main aim is to predict when a user might login next in future. That is i need to predict "Time". I ...
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### Estimating median survival times from Kaplan-Meier plot inspection

I've gone through the various questions relating to Kaplan-Meier plots and survival estimates, but I haven't really been able to find anything to help with this specific scenario. Sometimes, when ...
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### Hazard function of a gamma distribution

The system we are working on is biological, more specifically the distribution of specific events across a chromosome. This can be thought of as 1D array (the chromosome) across which points can be ...
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### Schoenfeld residual independent of time?

I've seen it claimed (e.g. in these notes ) that "Schoenfeld residuals are, in principle, independent of time." Can this be right? Consider the following situation: You are using a Cox model to ...
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### Impute missing values using aregImpute

I have a data frame with 61 columns. Some data is missing. I read in Steyerberg's book about aregImpute in Hmisc. I used it with ...