How to create a survival curve from tabulated survival data.

Prism is all set up to create and compare survival curves. To do this, enter one row for each subject on a table formatted for survival curves. To learn how to do this, create a Survival table from the Welcome dialog, and choose a sample data set (which comes with instructions).

But what if you (or someone else) has already computed the percentage survival at each time point. You want to enter these survival results, rather than raw data for each subject. With such data, it is not possible to compare survival curves or to compute confidence intervals or bands. Those calculations require knowing the data for each subject (or at least the number of subjects followed at each time point). But it is easy enough to plot these data as survival curves. 

To plot already-computed survival data, create an XY table (not a special table for Survival data). Enter the times (durations) into X, and the percentage (or fractional) survival into the Y columns. Then go to the graph, and fine tune the appearance. Note that Prism lets you connect points with a staircase curve: