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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Observed information matrix in Cox model with constant baseline hazard

I am trying to explore properties of Cox model with (parametric) constant baseline hazard function. So the hazard function for the model is $\lambda(t|Z_i) = \lambda_0(t) ...
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1answer
16 views

Can I work out the numbers in the groups, based on the results of hazard ratio?

I need to extract data from a paper that report a hazard ratio=0.72, 95% CI=0.57, 0.92, p=0.010. Knowing that the one group that did better had 255 individuals and the other 252. How can I find out ...
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1answer
26 views

Applying Cox's Porportional Hazard model

I have a dataset on two groups. Group 1 (18 subjects) and group 2 (5 subjects). Each subject in the groups had to perform a number of tasks which was timed. The time restriction was 60 seconds. If ...
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1answer
39 views

What kind of model should I use for churn risk prediction?

I have a data set containing many client's id, and its behavior characteristics measured each month before churn or censored. Data looks like: id || lifetime period || folow-up time before churn of ...
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17 views

Cox PH model with quadratic effect interpretation

I'm fitting a Cox model with non-linear continuous variable with and without a time varying effect (to correct non-PH). My goal is to get risk ratio (hazard ratio) associated with X. I have the Cox PH ...
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15 views

How do you calculate the compared populations in cox hazard ratio problems?

Take a look at the following open-access paper http://www.ncbi.nlm.nih.gov/pubmed/26506242 I've tried doing cox regression in both R and SPSS but I cannot get ...
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1answer
69 views

What does the p value mean for Cox hazard ratio? [duplicate]

I am puzzled about the interpretation of P value in the Cox hazard ratio analysis. I read from literature that the P value is to "reject the null hypothesis that HR=1". However, in many cases, we have ...
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25 views

Problem with initial guess in Newton-Raphson iteration method

I'm working on estimating the four parameters of Exponentiated Modified Weibull Extension Distribution introduced by Sarhan and Apaloo (2013) with the Maximum Likelihood Estimation (MLE). Because the ...
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72 views

Nonparametric Estimation of the Hazard Ratio

I am not sure if this is appropriate here, but I'm hoping someone would be able to help. The following is an excerpt from the following paper "Nonparametric Estimation of the Hazard Ratio" by ...
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33 views

Comparing plot from survfit with plot of cox baseline hazard converted to survival rate

Based on the initial question: Cox Baseline Hazard I would like to plot survival curves by gender for this model using the kidney dataset. Following the example codes, I subset the dataset by gender, ...
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1answer
56 views

Categorical variable with hierarchical structure - Cox regression

What is the best way to build a cox model with a categorical variable that has a hierarchical structure (20 levels).
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23 views

Survival analysis book with R language

I am looking for a good book for survival analysis in R . Also, I wnat the focus to be on cox model and its extensions). Better if free
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15 views

How to interpret parameter in proportional hazard model?

How can I show that $b$ in this proportional hazard model $y=1-x^{e^{bz}}$ is the percent change in $y$ with a unit change in $z$? For brevity, I have neglected to show the functional form of $x$, ...
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1answer
26 views

Many categorical variables in Cox regression model

I am using Cox regression to model my data (time to an event). One of the covariates has 29 categories. I would like to compare the categories to one another and identify which category has shortest ...
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13 views

How to model “time-to-adopt”

I have data of many users (several millions) and the timing of when each of then has adopted a product. All of then have adopted so it is not a matter of the propensity to adopt - in their case they ...
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1answer
26 views

Need help to simulate Survival Times with a time-varying Covariate

I would really appreciate if someone can help me figure this out as I have been working on it for few days now and I don't know what I'm missing that it's not working. Basically, my goal is to sample ...
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19 views

Survival/hazard models with multiple hazard occurrences for each individual

I'm new to survival/hazard models. My data contains information about many users (millions), each of them has done some action (let's say, for simplicity - adopted a product). Some of the users did it ...
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1answer
35 views

How to interpret hazard ratios for a cox model with 100% failure rate

I am studying the impact of temperature on the onset of flowering of trees. I am using a cox model for time dependent covariates as implemented in the R package survival. I only have one (cumulative) ...
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1answer
42 views

are hazard ratios additive?

I have data from Cox regression which indicates that compared to a baseline condition condition A => has hazard ratio= 2 condition B => has hazard ratio= 6.5 Is it possible to say if condition A and ...
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2answers
67 views

What is the definition of “death rate” in survival analysis?

I am reading a text on survival analysis (Smith's 2002 Analysis of Failure and Survival Data). All concepts like hazard function, survival function, density of survival variable $Y$ are rigorously ...
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1answer
62 views

Survival Analysis: Cox Proportion Assumption

I know i'm missing something here, please help me understand the cox proportion assumption. What is the point of having a hazard rate function over time if it first has to meet the cox proportion ...
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1answer
40 views

Calculate confidence interval for hazard ratio given maximum likelihood and standard error

I'm doing a meta-analysis and one of the studies presents the hazard ratio (HR) with the maximum likelihood estimate (MLE) with its standard error (SE). The rest of the studies give the HR and the ...
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1answer
52 views

log hazard function in R

I'm trying to write out the log hazard function of the lognormal distribution and use this in R. Using the survival function: and the hazard function: I have the following for the log(hazard): ...
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24 views

functional form for modeling hazard function

What functional form do you suggest to model this hazard function? Can it be a quadratic form, even tough it's skewed?
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78 views

Converting log hazard function to survival probability

I am currently working through a survival problem and I wanted to get some advice with how to proceed. I wanted to estimate survival probabilities over time based on knowing only the $\log({\rm ...
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32 views

Time Series Shocks with Exponential Decay

Imagine a piano key played in an auditorium: The amplitude of the sound wave is perhaps highest in the first milliseconds, then slowly decays to zero if no other notes are played. If other notes are ...
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50 views

Difference between survival and hazard

I am trying to find an intuitive explanation of the difference between the hazard and survival rates? Are the two the same thing but expressed differently?
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62 views

How to get event hazard rates from a survfit object for sample size calculation

I want to calculate the sample size for a clinical trial (right-censored time to event data). I have data of a retrospective analysis and would like to use nSurv ...
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7 views

Multilevel Model for time to event data

How can I write the general equation for multilevel parametric proportional hazard model and multilevel cox proportional hazard model?
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334 views

The difference between average and marginal treatment effect

I have been reading some papers, and I am unclear about the specific definitions of Average Treatment Effect (ATE), and Marginal Treatment Effect (MTE). Are they the same? According to Austin... ...
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1answer
31 views

How to interpret hazard ratios for time-segmented variables?

I'm constructing a Cox regression model where patients were randomised to treatment or placebo, and then had certain continuous covariates measured at multiple time points through the course of the ...
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47 views

How to scale the Hazard Function?

Please help me understand this: Imagine one has a population of 30 subjects, and their failure times are described by the Weibull distribution with parameters i.e: $ \alpha=1.9,\ \beta=1.3 $. ...
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35 views

Modelling retirement of employees by age where only data of very view years are available

We want to model the retirement of employees. We have data on a yearly base for about 20,000 employees by age and some other properties. There are two questions: Suitable Approach In most cases we ...
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1answer
64 views

Non-proportional Weibull hazard model with heaviside functions

I am trying to model a non-constant (and non-linear) hazard ratio between two groups (Group A and Group B), assuming that the baseline hazard for one of the groups can be described with the Weibull ...
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2answers
55 views

Understanding Hazard Function Values Exceeding 1

I keep running into problems in understanding hazard rates. I know, for example, that in a strict sense a hazard rate is not a probability and it is continually mentioned that because of this the ...
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2answers
230 views

Is there any guideline for interpreting a hazard ratio as 'small', 'medium' or 'large'?

I would appreciate if anyone can share a reference that discusses magnitudes of hazard ratios as effect sizes. Specific subject matter obviously weighs in when trying to determine what a relevant ...
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1answer
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(1) A flight has a 1% chance of crashing. (2) It's scheduled to fly 200 flights that week. Does (2) add any info re: your risk?

And assuming that: a) This is that particular airplane's very first flight, ever (not just for the week). b) Any distributions involved should be discrete in the sense that they should be functions ...
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34 views

Proportional hazard assumption in survival analysis

Which is the best method to check proportional hazard assumption in survival analysis?
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1answer
99 views

expectation of $e^{-x}$ when x is log-normal

I'm trying to find the expected value of $ e^{-x} $ when $ x$ is log-normal. I know that if $ x \sim N(\mu, \sigma) $ then $ E[e^x] = e^{\mu + \frac{1}{2}\sigma^2} $, the expectation of a log-normal. ...
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29 views

chance of death year by year or a hazard function

I have a large birth cohort (about 250K) of firms organised into four size-bands (classified by the number of jobs). There are 15 years of annual observations, and by age 15 about 90% of firms are ...
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23 views

Life table based on age groups

I am working on panel attrition (loss of respondents at each wave of follow-up of a longitudinal survey). A multivariate model (discrete-time event history analysis) to analyse panel attrition is ...
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2answers
514 views

Modeling customer churn - Machine learning versus hazard/survival models

Is their any rational (theoretical, substantial, statistical) to opt for either machine learning or hazard models when modeling customer churn (or more general, event occurences)?
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2answers
92 views

P-value versus Exp(B) value in Cox regression analysis

I performed Cox regression analysis for two Biomarkers. Both were significant (p<0.05). Biomarker 1 showed higher significance but lower Exp(B)=hazard ratio value than Biomarker 2 (see below). ...
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1answer
104 views

What is the difference between the “Hazard Rate” and the “Killing Function” of a diffusion model?

I posted the same question in Mathematics. I will update both posts if we get any answers. Link here. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ What is the ...
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Computing hazard ratio between groups adjusting for other confounding variables

I have groups formed based on BMI; consider the standard Underweight, Normal, Overweight, etc. groupings for BMI as you might see for classification. I'd like to form a hazard ratio for comparing any ...
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1answer
124 views

Fluctuations in hazard function at high (x) values

Using a best-fit algorithm, i've obtained gamma-distribution parameter MLEs for my data (scale and shape). When evaluating the hazard function, calculated as the PDF divided by the reciprocal CDF, ...
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47 views

Cox Regression Hazard Ratio in Percentiles

I computed a Cox proportional hazards regression in R. cox.model <- coxph(Surv(time, dead) ~ A + B + C + X, data = df) Now, I got the hazard ratio (HR, or ...
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1answer
45 views

Calculating group size from hazard ratio

I am undertaking a systematic review and as part of the data extraction process I would like to know how many patients were analysed in the treatment and control arm (in a particular subgroup). In one ...
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0answers
216 views

Time-dependent coxph output and making predictions in R

I'm trying to use a Cox proportional hazard model to predict the time until an employee terminates from an organization. There are a bunch of covariates (~20), some of them time-dependent. So I've ...
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15 views

Point process models

Two of the popular models for analyzing point process data are Cox and Hawkes processes. My question is how do we compare the statistical properties of these two processes as they both can be ...