## What is Coxph function in R?

R function to compute the Cox model: coxph() method: is used to specify how to handle ties. The default is ‘efron’. Other options are ‘breslow’ and ‘exact’. The default ‘efron’ is generally preferred to the once-popular “breslow” method.

**What is cumulative hazard function?**

We can say that the cumulative hazard function: measures the total amount of risk that has been accumulated up to a certain point of time t. provides the number of times we would mathematically expect the occurrence of the event of interest over a certain period if only the events were repeatable.

**How is hazard ratio calculated?**

As a formula, the hazard ratio, which can be defined as the relative risk of an event happening at time t, is: λ(t) / λ0. A hazard ratio of 3 means that three times the number of events are seen in the treatment group at any point in time.

### How do you interpret a hazard ratio for a continuous variable?

With a continuous variable, the hazard ratio indicates the change in the risk of death if the parameter in question rises by one unit, for example if the patient is one year older on diagnosis. For every additional year of patient age on diagnosis, the risk of death falls by 7% (hazard ratio 0.93).

**What is proportional hazard assumption?**

The proportional hazard assumption is that all individuals have the same hazard function, but a unique scaling factor infront. So the shape of the hazard function is the same for all individuals, and only a scalar multiple changes per individual.

**How do you interpret Cox proportional hazard coefficients?**

The coefficients in a Cox regression relate to hazard; a positive coefficient indicates a worse prognosis and a negative coefficient indicates a protective effect of the variable with which it is associated.

## What does Surv do in R?

2 Basic Survival Analysis A key function for the analysis of survival data in R is function Surv() . This is used to specify the type of survival data that we have, namely, right censored, left censored, interval censored.

**What is Survreg?**

survreg: Regression for a Parametric Survival Model.