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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Tail problem with hazard function

Before doing a more advanced survival analysis, I generated an exponentially distributed variable in Stata and used the following code to get a constant hazard rate graph: "sts graph, hazard" I get ...
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Comparing failure rates between 2 products with different number of deployed equipment

I have the following scenario, which I am trying to better understand. There are 2 different brands or groups of devices performing the same functionality as such: - Product/Brand 1 has 4,323 devices ...
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Interpretation of the hazard ratio in a spline model on continuous exposures

I am having trouble interpreting the output from a Cox proportion hazard model with a spline term on a continuous exposure. In the below example (pseudo-code from ...
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19 views

Cox PH Modelling: How important are ties to the end result?

I am working on create a survival model using Cox PH, but am concerned with the limitation of the continuous time requirement. In my dataset there are often ties. For example, out of 35000 records, ...
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33 views

How to demonstrate biased estimates of linear regression vs cox proportional hazard survival analysis in R?

I want to perform a really simple simulation of right censored data. Then I want to draw a kaplan meir survival curve and do a cox proportional hazards test. Then I also want to perform a simple ...
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51 views

Hazard function, survival function, and retention rate

What is the difference between the hazard function, survival function, and retention rate in survival analysis?
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Are there any possibilities to check model assumptions or any diagnostic for the proportional hazards model with correlated times?

As far as I know, regular proportional hazards model have assumptions that times have to be independent, hazards for each variables should be proportional and there should be noninformative censoring. ...
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Can proportional hazard regression predict the S(t) of subjects?

In my understanding, cox PH model can only give estimates of coeffs of regressors and then interpretations can be drawn. Since it does not assume a base hazard function, it cannot give an estimated ...
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32 views

Some doubts about survival analysis

I'm struggling to perform a correct and unbiased survival analysis, but I have some doubts. Data I observe a population of posts on a blog within a temporal window $[T_{0}, T_{final}]$. Each post ...
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1answer
44 views

What do these probabilities mean in lay language? A HR of 0.419 means what?

The adjusted hazard ratios (HRs) for dementia were significantly inversely associated with increased daily or total equivalent statin dosage. The HRs for the three tertiles of mean equivalent daily ...
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Ordered Hazard Model in a 2-stage selection regression?

I'm writing with what is probably a pretty dumb question. But Google searches aren't revealing what I'm looking for, so I thought I'd come to the experts! Context I am interested in looking at ...
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Cause-specific hazard in R

library(cmprsk) library(muhaz) set.seed(2) time <- rexp(100,2) cause <- sample(0:1,100,replace=TRUE) mod = muhaz(time,cause) plot(mod) The above R code ...
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Discrete survivor function expressed in terms of hazard

Let $T$ can take on values $t_1,t_2,\ldots,$ with $0\le t_1\le t_2,\ldots,$ and let the probability function be $$f(t_j)=Pr(T=t_j),\quad j=1,2,\ldots$$ The survivor function is then $$S(t)=Pr(T\ge ...
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51 views

Fractional polynomials in PHREG procedure

For regression analysis by fractional polynomials i used the PHREG procedure in SAS. But it didn't give any Hazard Ratio values. Is it normal or any mistake in my code? ...
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45 views

Age-matching for 2 samples in Cox Regression

I have 2 samples with a very significant mean age difference: Sample0: less-invasive,lower-risk surgery. mean age = 70. n=159 , deaths = 24 Sample1: higher-risk surgery. mean age = 60. n=86, deaths ...
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52 views

Which model to use for survival analysis when there are different times of entry into the sample?

I have a data set containing the trades executed by many traders as follows: ...
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73 views

Differences between logistic regression parameter estimates and Cox-proportional hazard parameters

We have been working on a survival analysis. We are examining tree seedling survival over a decade with annual to biannual census intervals. We have been using the package coxme in R for a mixed ...
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25 views

Bivariate gamma distribution with one parameter marginal

Suppose two random variables X,Y>0, have a joint gamma distribution. Its marginal for X is G(a,b) and that for Y is G(a,c). For identification purposes, normalization is needed.does anyone know if ...
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Hazard ratio can be computed from shrinkage estimators?

I am using LASSO in survival analysis. I wonder if it is valid to compute a hazard ratio (HR) from a lasso coefficient, that is, $\text{HR} = \exp(\text{lasso coef})$? Thank you for any help!
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1answer
99 views

Average hazard rate with Cox proportional hazard model always larger than the hazard rate without any explanatory variables?

I am estimating a Cox proportional hazard model with and without explanatory variables. Without explanatory variables, the hazard rate is just the proportion of all individuals that failed at time ...
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39 views

How to calculate Hazard Ratio from Kaplan Meier curve

Is it possible to calculate the Hazard Ratio, Log[HR], and SE for overall survival (OS) using data from a manuscript that presents Kaplan Meier curve for OS? Usually these manuscripts present the ...
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33 views

Implication of Hazard Rate?

So from my understanding, the hazard rate is not a probability but a rate of an event happening at any one period of time. Can someone please tell me the implications of a hazard rate value. Would ...
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How to show that the cumulative hazard function is equal to the formula below?

I need help to show the equation below. $$H(t)=ln[\frac{mrl(t)}{mrl(0)}]+\int_{0}^{t}\frac{1}{mrl(u)}du$$ where mrl is the mean residual life using $$h(t)=\frac{\frac{d}{dt}mrl(t)+1}{mrl(t)}$$
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Is the magnitude of the hazard ratio change reflective of survival function change?

I need to know the change in survival caused by increasing inbreeding in my study group. As my model has random effects, and as coxme has no easy ...
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1answer
98 views

How to conduct Cox PH stratisified by matched pair in R

I am wanting to calculate hazard ratio in a matched cohort design. For such I am using the coxph() function in R. But I have been recommended to stratify by matched ...
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1answer
360 views

Find the mode of a probability distribution function

I am trying the find mode of a probability distribution function given by \begin{equation} g(x/\alpha,\beta,\sigma)=\frac{1}{\Gamma \left( \alpha ...
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152 views

Cox discrete time regression model question

Cox's 1972 publication Regression Models and Life Tables links logistic regression to an extension of the discrete time proportional hazard model. I do not understand how Equation (21) in the ...
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1answer
34 views

Study Length Over-Estimating Hazard Ratio?

Are cox model studies over too long a time-scale at risk of over estimating (or under estimating) a covariate's effect on hazard? I'm studying inbreeding in a captive animal population. Some ...
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1answer
138 views

What does muhaz return?

A pretty basic question. I have read somewhere that the muhaz function in muhaz package will return the baseline hazard rate for COX model. The muhaz document states that it "Estimates the hazard ...
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1answer
52 views

Estimating mortality using Cox model with baseline

I have been reading online notes and papers on how to build survival models using CPH, and I think I've a good idea how things work. However, there are two questions I still have in mind: 1) let's ...
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2answers
402 views

How to calculate the HR and 95%CI using the log-rank test in R?

The R survival package is very useful to do survival analysis. And I know the survdiff function can be used to compare the difference of survival time in two or more groups. And the p-value number can ...
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Hazard ratios for three groups - does deleting one group affect the remaining ratio?

My study originally had 3 groups, x , y and z. Hazard ratios were reported for x vs y, x vs z and y vs z. If we remove group z from the study, would the x vs y hazard ratio change? If someone can ...
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78 views

Survival analysis where P(event) < 1

Suppose you are interested in analyzing time to event data for a sample of patients. You are interested in the time elapsed until a patient contracts an illness. However, a majority of patients will ...
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different HRs and corresponding CIs with cph and coxph

I tried a model using cph and coxph: ...
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Is it possible to add 2 ore more Hazard factors?

I'm a general practicioner and I'm trying to estabilish a conection between interarm sistolic blood pressure difference with cardiovascular disease but i dont have time to wait 10 years or more to ...
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31 views

Compute the cumulative hazard of a time interval

I'm a little confused in calculating the cumulative hazard within a time interval. We know that $H(t)=\int^{t}_{0}h(u)du$, if I have $\Delta t=t_1-t_0$ (1) $H(\Delta t)=\int^{\Delta t}_{0}h(u)du$ ...
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198 views

Is it possible to construct a discrete-time multilevel hazard model in R?

I'm trying to run a discrete-time multilevel hazard analysis comparable to the model proposed by Barber et al. I am attempting to model the hazard of migrating internationally using predictors at the ...
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It it possible in R to specify a regression formula for the hazard rate for a survival analysis model?

I am currently trying to fit a survival analysis model which has the following survival function: $S(t) = \lambda_i e^{-\lambda_i t}$ but with $\lambda_i = e^{\beta_0 +\beta_1 log(1+X_i)}$ where ...
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1answer
33 views

Calculate Hazard Ratio Manually for Continous Covariate

I found an example for manually calculating the hazard ratio when there are two groups. ...
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Outliers in proportional hazards model

How can one easily found an outlier in PH model and why are they so important? Can anybody give me some advice or suggest which R function may I use? Thanks for comments and help.
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Using two hazard ratios to make third comparison

I have two sets of hazard ratios (with confidence intervals), one comparing risk of developing a cancer between current smokers and never smokers, and another comparing former smokers to never ...
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estimate conditional time-to-event for recurring event history model

I have a sample of individuals for whom I have measured the time at which they display a particular behavior. This behavior is recurrent (it is not fatal). I have modeled these events with ...
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Negative Regression Coefficent (Cox Regression)

I'm doing a Cox regression analysis in order to verify the role of two variables on the prediction of disease conversion. Previously, I did a ROC analysis and a logistic regression. All these methods ...
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Showing $ λ_V(x) \leq min\{λ_1(x),\cdots,λ_n(x)\}$ Hazard function

Suppose $X_1, \cdots, X_n$ are independent, nonnegative continuous functions, each $X_i$ has hazard function $\lambda_i(x)$. If $V=\max\{X_1, \cdots, X_n\}$, I need to show that ...
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Evaluating Proportional Hazards with time-dependent variables

I'm doing survival analysis and using the survival package from R to do it. I have 7 variables, 5 of which are time-dependent (all except sexo and peso). Here is my model: ...
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predicting manufacturing survival time

My task is to improve widget quality from a high volume manufacturing process. The survival data is 99% right censored, since most products do not fail, and rapid analysis long before failure is ...
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How to reconcile SAS hazard ratio standard error with actual value

I am trying to replicate the "C3 Contrast" (Output 66.3.7) at the bottom of: http://support.sas.com/documentation/cdl/en/statug/63962/HTML/default/viewer.htm#statug_phreg_sect048.htm I am able to ...
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339 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. ...
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176 views

Hazard and density function in survival analysis with discrete time

I am running a survival analysis with descrete time. For that purpose I use the R package survival with this function ...
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Selection correction variable (non-randomly selected sample / bias) and Cox regression

I found an approach to calculate a selection correction variable for a Cox regression (Lee 1983. Generalized econometric models with selectivity. Econometrica 51: 507–512.): $$ λ = \phi \frac{ ...