# Questions tagged [hazard]

In survival analysis, the hazard rate at time $t$ is the instantaneous probability of death at $t$, conditional on survival until $t$.

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### Cox regression in R with time dependent covariates [closed]

I have a dataset consisting of 100 companies loaded in R that looks like the following: COMPANY_NAME SECTOR COUNTRY ASSETS2018 ASSETS2017... ASSETS2010 DEBT2018 ... DEBT2010 TAKEOVER2018 ... ...
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### Computing discrete survivor functions

I am trying to understand the survivor function for a discrete point process, but I am finding two conflicting definitions. Any clarification would be much appreciated. For illustration purposes, ...
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### How to go about interpreting time-varying co-variates in survival analyses?

I'm pretty new to stats.. been working with cox models and getting a little confused. 1) Why do they occur? 2) How might one interpret/clinically translate a time-varying co-variate for cox models? ...
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### Breslow estimator coded in R from linear predictors

I want to calculate the Breslow estimate of the cumulative baseline hazard at a time t on R either 'by hand'. I know this is possible for the coxphobjects with the <...
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### Choosing a distribution for parametric hazard modeling

I have a question concerning determination of the baseline hazard function in a parametric survival regression such as Exponential, Weibull, e.g. Is there a way to determine which one is best? I have ...
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### what kind of survival regression model should I use?

I have a data set where I have a duration and time to event column. I also have covariates. My aim is to measure the effect size of the covariates(in terms of hazard ratio) calculate an interval, ...
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### Non-monotone Survival Function?

I was given the task of plotting the graph of a survival function with the following details defined. hazardrate (lambda) = λ(t) = 0.2 (1 + sin(tπ/12)) the underlying process is exponential I am ...
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### How to extract cumulative hazards from mixed-effect survival models?

I'm struggling to extract cumulative hazards from mixed-effect Cox models in R. I managed to extract survivals for each random level separately, but is there a way to obtain overall survivals ...
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### Calculating the probability distribution for Hardware defects based on history of defects

I'm writing a study about Hardware status in my institution. I've gathered data about hardware failures over time (I know how many failures happened each semester each year on a specific hardware ...
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### How to simulate from a step (simple function) hazard function?

I have a step hazard function $h(t)$ (a simple function that jumps at specific times and it is constant between those jumps). Something like: How can I simulate survival times from this hazard ...
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### test of difference (equivalence) between pairs of hazard ratios derived from two models

I have two stratified cox proportional hazards regression models each restricted to data on men and women, respectively. Both models have the same covariates and the data on men and women come from ...
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### Predict event probabilities and visit times in cox regression with gap time approach

I run a cox model on my data looking at times between gym visits. I want to predict the probability of a customer visiting the gym at a specific point in time and also the number of visits in a given ...
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### Model probability [virus infection] based on two interconnected events

Suppose we study the influence of two interconnected events on the probability of contracting a virus. The probability depends on two things that must necessarily be present: 1) the person goes to a ...
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### Need help in understanding the results of function survfit, from package rms, on cox proportional hazard model with time-varying co-variates

I have developed a cox-proportional-hazard model with fixed and time-varying covariates. Due to the time-varying covariates, I have adopted the (start, stop] coding as described in the survival ...
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### Definition of predictive hazard function?

In a Bayesian context, the posterior predictive probability density function is $$f_p(t) = \int f(t\mid \theta)\pi(\theta\mid \text{Data})d\theta,$$ where $\pi(\theta\mid \text{Data})$ is the ...
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### Testing for Constant Hazard Function

My colleagues and I have some unemployment data, and we'd like to test the hypothesis that it's drawn from a memoryless distribution (= constant hazard function). Is there a standard test for this? (...
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### Set new reference level for hazard ratios

I run a Cox Regression and afterwards, I predicted the Hazard Ratio (HR) for the predictor values 1 to 10. My data looks something like this: ...
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### How to model the Hazard Rate?

I'm interested in modeling the Hazard Rate $\lambda$ from a Survival dataset so I can calculate the Cumulative Distribution $F(t)=1-e^{-\lambda t}$ but I'm not sure how to go about computing $\lambda$...
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### Is the Cumulative Hazard Function simply estimated using the Empirical CDF?

I'm just starting to learn about Survival Analysis and I understand the theoretical proofs but I'm still unclear about how to do some of the estimations practically.
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I have a Weibull proportional hazard model with fitted parameters $\lambda$ and $k$ and a time dependent covariate $x(t)$ with fitted coefficient $\beta$, such that the hazard function is given by, $... 0answers 43 views ### How is a survival model with constant baseline hazard and time varying covariates called? The data situation: Supose in different forests data have been collected. These data include the temperature at different time points, the hours of rain, the type of forest and whether the event (a ... 0answers 37 views ### Time and events in a Cox model I am going to perform survival analysis using the Cox model, but I have some doubts about the input data. The data have the following structure: ... 0answers 11 views ### Likelihood function for a unit$i$with death at time$t_{i}$and non - death at time$t_{i}$The survival function with respect to time is defined to be$S(t) = 1 - F(T) = \int_{t}^{\infty}f(x)dx$With a bit of algebraic manipulation, one arrives at the time dependent hazard rate ... 0answers 9 views ### It is possible to calculate what the expected hazards ratio would be for a subgroup if I am assuming the subgroup is an independent variable? I am interpreting a placebo-controlled comparative study. For the primary endpoint: Overall n=8179 Hazards ratio: 0.75, 95% CI: 0.68 - 0.83 Gender is assumed to be an independent variable in ... 0answers 21 views ### Does prediction-at-the-means give the correct survival function in the long run? If you fit a Cox model, it's possible to come up with an estimate of the baseline hazard function using the Breslow step estimator. In R, this is the basehaz ... 1answer 393 views ### What does 'km' transform in cox.zph function mean? I'm trying to understand how cox.zph function in r programming language works and I find myself not knowing what km transform ... 0answers 22 views ### Hazard ratio for continuous variable I have a HR of 0.65 (0.46-0.92) and my explanatory variable is age (weeks of age). Time, event ~ age modeled with a flexible semiparametric model. My interpretation is that for each week elapsed, ... 2answers 465 views ### Interpreting hazard ratios in stratified models I am unsure how to interpret hazard ratios from cox-proportional hazard models that include 1 or more stratified terms. For example, say I run a cox regression with treatment as a covariate and ... 0answers 33 views ### Given competing risks, what is the probability of an event within d steps from time t? In competing risk analysis, we can only identify the cause-specific hazard and functions of that hazard. The cumulative incidence function (CIF) is a function of the cause-specific hazards. Because ... 2answers 301 views ### How does the probability of events change if an event does not occur Suppose that someone tells me I will collect$\$100$ dollars within some time interval. Those time intervals are 1 to 7 days, 8 to 30 days and eventually after 30 days. Let $A$ be the event I ...
Given a hazard ratio($HR$) as $$𝐻𝑅_{b}=ℎ𝑎𝑧𝑎𝑟𝑑(b)/ℎ𝑎𝑧𝑎𝑟𝑑(a)$$ and another hazard ratio as $$𝐻𝑅_{c}=ℎ𝑎𝑧𝑎𝑟𝑑(c)/ℎ𝑎𝑧𝑎𝑟𝑑(a)$$ How can we obtain the hazard ratio between $b$ and $c$ ...