BookmarkSubscribeRSS Feed
GordonC_SAS
Calcite | Level 5

I have two binary variables: treatment arm (arm 1, arm 2) and event (Yes, No) for each participant. I transformed my participant-level data into a long format summary data (so now I have 3 variables: count, arm and event). My goal is to compute the relative risk of event in arm 1 comparing to arm 2, and the exact confidence interval. The problem is the frequency of the event in arm 2 is 0 (no one had event in arm 2) so I always get infinite RR. And upper bound of my confidence interal goes to infinite as well. Is there a way to avoid this problem? I learned that proc freq would add 0.5 to each frequency to ensure that the statistics is defined when there is 0 frequency table cells but I couldn't figure out the code. 

 

Here is my code:

 

proc freq data=data1;
weight Count;
tables arm*event ;
exact RELRISK;
run;

4 REPLIES 4
ballardw
Super User

Can you share the cell counts you are getting in the 2x2 table?

GordonC_SAS
Calcite | Level 5

my cell count frequencies are:

 

arm 1, event = yes: 5

arm 1, event = no :  70

arm 2, event = Yes: 0

arm 2, event = No: 26

Ksharp
Super User
proc freq data=data1;
weight Count/ZERO;
tables arm*event ;
exact RELRISK;
run;
GordonC_SAS
Calcite | Level 5

I'm still getting infinite relative risk with the ZERO option. 

hackathon24-white-horiz.png

2025 SAS Hackathon: There is still time!

Good news: We've extended SAS Hackathon registration until Sept. 12, so you still have time to be part of our biggest event yet – our five-year anniversary!

Register Now

How to Concatenate Values

Learn how use the CAT functions in SAS to join values from multiple variables into a single value.

Find more tutorials on the SAS Users YouTube channel.

SAS Training: Just a Click Away

 Ready to level-up your skills? Choose your own adventure.

Browse our catalog!

Discussion stats
  • 4 replies
  • 2659 views
  • 0 likes
  • 3 in conversation