How to Create a Survival Curve

This post will take you from a variable that shows numeric values, such as the number of days to trial a product:

To a state where you can visualize the probability of an event at a certain time interval, such as the proportion of people who have yet to purchase at each point in time. Survival curves are also known as Kaplan-Meier curves:

Requirements

• A numeric variable.

Method

1. Go to Create > R Output.
2. In the object inspector, go to Properties > R CODE and paste in the following code and click Calculate.

   library(survival)
   surv.days = Surv(Days)
   surv.fit = survfit(surv.days~1)
   #Set Plot title
   plot(surv.fit, main = "Kaplan-Meier estimate with 95% confidence bounds (86% of data)",
   #Set x-axis title
   xlab = "Days since trial started",
   #Set x-axis maximum and minimum limits
   xlim = c(0, 180),
   # Set y-axis title
   ylab = "Survival function")
   grid(20, 10, lwd = 2)

In the code above, "surv.days = Surv(Days)", Days is the name of your numeric variable being used to create the density plot. This must be updated with the variable's Name in your data set.