Proc Lifetest Stratified Vs Unstratified log rank test

[Kollon]

Please give an example of Stratified Vs Unstratified log rank test SAS code. Thanks!!

[ChrisHemedinger]

The LIFETEST documentation features a few examples, some of which use the STRATA statement. 

For example: 

• 72.1 Product-Limit Estimates and Tests of Association (stratified by Cell type).  Example output:

Rank Statistics
Cell	Log-Rank	Wilcoxon
adeno	10.306	697.0
large	-8.549	-1085.0
small	14.898	1278.0
squamous	-16.655	-890.0

Compare to:

• 72.3 Life-Table Estimates for Males with Angina Pectoris (no strata used)

(Disclaimer: I'm no expert on LIFETEST -- just reading the syntax used)