About Survival tables

What is a survival table?

On a survival table, you enter information for each subject. Prism then computes percent survival at each time, and plots a Kaplan-Meier survival plot (and also compares survival with the log-rank and Gehan-Wilcoxon tests).

Analyses performed with survival data

Prism automatically performs these analyses from your data, so you do not need to (and shouldn't) choose an analysis to perform.

•	Kaplan-Meier

•

Log-rank

•	Wilcoxon-Gehan

Kaplan-Meier survival curves plot fractional survival (Y) as a function of time (X). It can be used to analyze the time to any event (usually death) that can only happen once. If you already have data organized in this way, enter it on a XY table.

Graph types from a survival table:

Example of a survival table:

Entering survival data

Each row represents a distinct subject. (You can optionally use row titles to identify the subjects.) Each column represents a treatment.

•	Enter elapsed time (usually in days) as X (Prism does not let you enter dates).

•	For each subject, enter a code for Y:

•	Enter ‘1’ for a subject if the event (death) occurred at the time entered into X.

•	Enter ‘0’ if the data are censored. Data are censored when you simply don’t know what happened to the subject after that time, or do know but can’t use the information.

For a more complete discussion of entering survival data and interpreting the results, see: How To: Survival Analysis