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How do you estimate a baseline hazard function?
The baseline hazard function can be estimated in R using the “basehaz” function. The “help” file states that it is the “predicted survival” function which it’s clearly not. If one inspects the code, it’s clearly the cumulative hazard function from a survfit object.
What is the baseline survival function?
Survival models can be viewed as consisting of two parts: the underlying baseline hazard function, often denoted. , describing how the risk of event per time unit changes over time at baseline levels of covariates; and the effect parameters, describing how the hazard varies in response to explanatory covariates.
What is the baseline hazard?
In lifelines, the baseline hazard is the hazard function when all covariates are set to the mean of the covariate. So that “baseline survival” in the graph is the “average” subject (which often has no real world meaning tbh, you can’t be 0.5 male). Thus, it makes sense to have prio=0 above the baseline survival.
How to calculate the baseline hazard of a Cox model?
If I consider a Cox model: I need the estimate of the baseline hazard. By using the built-in survival package R function basehaz (), I can easily do it like this: But if I want to write a step by step function of the baseline hazard for a given estimate of parameter b how can I proceed? I tried:
How to calculate the cumulative hazard rate in basehaz?
Apparently, basehaz () actually computes a cumulative hazard rate, rather than the hazard rate itself. The formula is as follows: where y ( 1) < y ( 2) < ⋯ denote the distinct event times, d ( l) is the number of events at y ( l), and R ( y ( l)) is the risk set at y ( l) containing all individuals still susceptible to the event at y ( l).
Which is a strength of a Cox model?
A Cox model was explicitly designed to be able to estimate the hazard ratios without having to estimate the baseline hazard function. This is a strength and a weakness. The strength is that you cannot make errors in functions you don’t estimate. This is a real strength and is the reason why people refer to it as “semi-parametric”…
Do you need an estimate of the baseline hazard?
I need the estimate of the baseline hazard. By using the built-in survival package R function basehaz (), I can easily do it like this: But if I want to write a step by step function of the baseline hazard for a given estimate of parameter b how can I proceed? I tried: But this does not give the same result as basehaz (fit). What is the problem?