Survival analysis is concerned with modelling the time before subjects change state, typically time until death or failure. One key feature of such data is that they can be censored, that is, some subjects will not have changed state before the study ends.

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52 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
29 views

Survival Curve vs Cox PH hazard levels discrepancy

This is a very high level question, hope it's not too general for this forum: Is it possible to have a greater risk (hazard) for a factor variable in a COXPH regression for one level against another ...
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10 views

Capture-recapture analysis with only one recapture event

I am analyzing within-season variation of the components of reproductive success looking at temporal changes and their relationship. I have a problem with pre-fledging survival (the survival ...
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1answer
43 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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0answers
7 views

Modeling mortgage prepayment behaviour using survival analysis

I am doing a study of prepayment behaviour on mortgage loans where the partial prepayment (curtailments) are very frequent and sort of normal behaviour as there are no penalties for such events. As a ...
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1answer
17 views

survival curve for a time-dependent predictor

I am doing survival analysis with a time-dependent predictor. I used an extended cox with heaviside function and got the hazard ratios. But now I am stuck on how to make the survival curve and to get ...
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1answer
64 views

Predict time of next purchase

I'm trying to build a model in R that will let me predict when a costumer will purchase a product again. For example, the training data list customers who purchased bikes. I want to predict when ...
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22 views

Interpreting the failure rate lambda(t) in a Weibull distribution.

I've fit a Weibull distribution to failure data, getting a $\beta = 4.374884$ & $\eta = 1244.936$. From here it's clear my failure rate is $\lambda(t) = ...
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15 views

Modeling attrition of customers - survival analysis?

I have a dataset of the following form: ...
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2answers
27 views

Is a pairwise Cox regression approach valid for small samples?

Firstly, some background on the dataset: I am performing survival analysis on a 28-event dataset. We found a genetic marker that predicts survival on a drug. Examining the data, the proportional ...
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12 views

Treatment of waiting time data with repeated observations for a finite time

A call center is open for 9 hours every day. My data are the times of occurrence of calls, divided in days. Some days are busier than the others and some days no calls at all occur. I have to estimate ...
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25 views

Upper limit of confidence interval

The estimated median response duration was 17.5 months (range, 0.0 to 19.6; 95% confidence interval [CI], 15.8 to not reached). The above is taken from a medical study. Why was the upper limit of the ...
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17 views

one-sided survival log rank test p-value

I want to compare two treatments for an oncology indication. I used a log rank test as two treatments (variable treatment) with time (variable month) and censor status (variable censor). Below is the ...
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1answer
28 views

Test of proportions - proportion with CI versus given value

I am working on one clinical trial, where the primary goal is to compare proportion of overall survival (OS prop) after 12 months between our study and other registration study. I computed the OS prop ...
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0answers
18 views

Can I use Cox PH regression to capture exogenous effect?

Can I use Cox PH regression where I have 'subjects entering the study at different point in calendar-time' and 'the covariates are exogenous which varies with calendar-time' ? Eg. To study the effect ...
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0answers
29 views

Poor survival analysis model fit with Gronnesby and Borgan

I have been experiencing issues with model fit. In my example, I have set up a time-varying (counting method) survival analysis model (Cox regression with ...
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0answers
7 views

Should stratified analyses be used when stratified randomization has been used?

I am considering a randomised controlled trial (RCT) where an experimental intervention A is compared to a bag of standard treatments, B, C and D (which range from intensive to minimal active ...
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1answer
26 views

How do I get interval-specific survival rates from an Andersen-Gill model?

I am using coxph in the survival library to create Andersen-Gill models. I am interested in getting interval-specific survival rates for my data. For instance, I ...
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1answer
22 views

Hierarchical Weibull model: choice of parameterization

I am experimenting with fitting a Bayesian hierarchical model using right-censored and Weibull distributed time-to-first-event data. However, I have some issues that might be related to the ...
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13 views

Survival with unknown birth time and large observation time resolution

Suppose at $t=0$, we have a box with nothing in it, then 8 hours after at $t=8$, we ook in the box and find inside $N$ cells that have appeared. Over these $N$ cells, $D$ are dead and $L=N-D$ are ...
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13 views

Discrete time survival applied to a fishery over several years. To pool or not to pool?

I am studying a fishery and trying to determine the exit behavior of fishermen over the season. This is a peculiar fishery as 90-95% of vessels start participating at the beginning and then drop out ...
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1answer
132 views

Estimate the number of failing components in a changing population

I'm working on a problem (using R) which involves estimating the number of failures in a population of components. I have information on the number of components that were added to the population in ...
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1answer
13 views

Lifetime simulation problem for late entry to the study

I was reading a dissertation where the author generates lifetimes ($T_i$) from Exponential distribution with parameter 2 (years). He sets a 5-year study period, so he simulates the censoring times ...
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1answer
47 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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19 views

Standard errors and confidence interval in cox regression model validation using RMS package

I am using RMS package of R to validate cox regression model with bootstrap. Please see the sample code below. I have three questions: (1) How do I request the standard errors and/or confidence ...
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22 views

confidence intervals for cox proportional hazards with 0 events in one treatment arm

We are performing a multivariate cox proportional hazards analysis with 6 covariates. Two of the covariates (Pre_ASCT_response2 and NGS_graft_MRD2) are binary covariates with 0 events in one ...
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1answer
15 views

How to compute standard error of the log-hazard in the baseline arm from an n-arm study

I'm trying to use GeMTC (a package for Bayesian Network Meta Analysis) for an analysis that mixes contrast-based data (Hazard Ratio;HR) with arm-based data (event counts). The documentation specifies ...
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68 views

Logistic Regression as an adjunct to Survival Analysis

As I understand it, survival analysis was created for situations where, if we followed everyone indefinitely, everyone reaches the "event" (death). Let's say that this isn't one of those situations - ...
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88 views

Inferring likely dates based on other related dates in incomplete data set

I'm taking my first steps in data science and machine learning. I'm experimenting with a project where I have no idea even what approaches I might start with, so I'd appreciate any leads: I have a ...
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2answers
34 views

Why use ln-ln plot in proportional hazard test?

I recently began studying survival analysis and there is something I am curious about. Why do we prefer to use the ln-ln survival curve rather than the survival curve in a proportional hazard test? ...
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1answer
107 views

Combining individual terms from the predict() function

I want to merge several variables' estimate and also calculate the confidence intervals from the survival:::predict.coxph function's output. Just like the the ...
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0answers
15 views

Right censored data, abundant in zeros for regression analysis

I am looking at conditioning to stimuli and there in the time taken to perform a certain task. The IV for this data is Conditioning periods ranging from 1-34 periods and the DV is the time taken for ...
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2answers
40 views

how can I focus the log rank test in a selected period of time of follow up?

I am using R survdiff (survival package). I would like to focus the analysis on the first 2 years of my survival curve (that is actually much longer, but with few cases in the long term and with ...
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15 views

Determine number of excess events in survival analysis

I have run a survival analysis on two group of people that saw different ads during an ad campaign. I would like to calculate the number of excess events that occurred due to the exposure to the ad. ...
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25 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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29 views

Survival Analysis - Improbable Exp(B)?

I'm currently conducting a survival analysis on my dataset. I have data on adoption of a new service and am using a Cox Proportional Hazard Model in order to account for right-censored observations. ...
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13 views

Analysis of time between events with time-dependent exposure

I have got this dataset with records of people who have suffered from two or more cardiac arrests. The first were registered in 1985 and the last record is from 2010. For each record, there is data on ...
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15 views

How to “deal” with functional form of covariate?

I am doing cox regression analysis and am confused with the different of implications of functional form using cumulative martingale residuals and use of cumulative residuals to assess ph assumption. ...
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18 views

Transformation of Adoption Timing / Post-Adoption Usage

I'm currently working on a project where I intend to simultaneously model adoption timing (a dependent variable which takes on a value of 0 ~ 5 operationalised as ...
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37 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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1answer
38 views

Calculating life time expectancy

How to calculate life time expectancy when not all patients have died. Kaplan-Meier provides a survival curve which is similar to cumulative distribution function but not the actual expectancy. For ...
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26 views

Would a contingency chi-sq test be useful in this case?

I am looking at mortality of caterpillars who were reared on different diets. I have the total number of caterpillars on each diet on the first day of observation, and then again on the final day of ...
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1answer
34 views

Interpreting interaction terms in Cox Proportional Hazard model

I am new to survival analysis, so forgive me if this questions is stupid - but I couldn't find the answer anywhere else. We are looking at readmission to a treatment program, which is defined as ...
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5 views

Uneven (right) censoring where the time of truncation is constant

I've collected data comparing the relative success of two different groups of participants on finding the answer to a difficult question. The problem is that not all the participants in the control ...
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16 views

how to calculate survival time and Event

If I have 10 wild type flies in a bottle and I study them for 13 days to see how many survive or die or are lost. Similarly i have 10 mutant flies in a jar and I observe the following die or are lost ...
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55 views

Censored Data Log Likelihood

Suppose we have a n random samples ($X_1,..., X_n$) from a negative exponential distribution. If lets say we have these n random samples are censored at t, such that ($X_1, ..., X_m$) are observed and ...
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20 views

Survival analysis for hospital visit

I have a survival problem involving three types of subjects. Each patient is classified based on their first procedure (“intent to treat”). I have a list of each procedure performed and the day ...
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0answers
59 views

Why are correlated observations not an issue in Cox regression with time-dependent covariates?

In the extended Cox model we can easily include time-dependent covariates $X(t)$. If we use counting process notation, this will result in multiple records per patient. Each record consists of (start, ...
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1answer
31 views

How to request predicted points for each patient based on nomogram in RMS?

I am generating nomogram for a survival analysis project using RMS package of R. A PI of the project would like to have predicted points for each patient in the sample predicted by the nomogram. Is ...
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42 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 $. ...