topic Trouble getting hazard ratio in Statistical Procedures https://communities.sas.com/t5/Statistical-Procedures/Trouble-getting-hazard-ratio/m-p/81196#M3894 <HTML><HEAD></HEAD><BODY><P>I am trying to get hazard ratio for a risk factor. Individuals with exposure had no events and individuals without exposure have 9 events. I have follow up time. when i use proc phreg, I don't get hazard ratio for risk factor. it comes up as "."</P><P>is there any other way to get HR in this case?</P><P></P><P>any help will be appreciated. </P><P></P><P>Thank you</P></BODY></HTML> Tue, 12 Jun 2012 21:32:28 GMT claw13 2012-06-12T21:32:28Z Trouble getting hazard ratio https://communities.sas.com/t5/Statistical-Procedures/Trouble-getting-hazard-ratio/m-p/81196#M3894 <HTML><HEAD></HEAD><BODY><P>I am trying to get hazard ratio for a risk factor. Individuals with exposure had no events and individuals without exposure have 9 events. I have follow up time. when i use proc phreg, I don't get hazard ratio for risk factor. it comes up as "."</P><P>is there any other way to get HR in this case?</P><P></P><P>any help will be appreciated. </P><P></P><P>Thank you</P></BODY></HTML> Tue, 12 Jun 2012 21:32:28 GMT https://communities.sas.com/t5/Statistical-Procedures/Trouble-getting-hazard-ratio/m-p/81196#M3894 claw13 2012-06-12T21:32:28Z Re: Trouble getting hazard ratio https://communities.sas.com/t5/Statistical-Procedures/Trouble-getting-hazard-ratio/m-p/81197#M3895 <HTML><HEAD></HEAD><BODY><P>No.&nbsp; The hazard ratio is not defined when you don't have any events in one group; your sample size is too small for PHREG.&nbsp; You might be able to force PHREG to provide an estimate by arbitrarily creating an event in an observation in the exposed group, but the estimate will be quite unstable.</P><P></P><P>Computing the required sample size for a survival analysis is pretty tricky, you need both an estimate of the event rate per group and how much censoring you will have (the latter is really hard to get a handle on).&nbsp; PASS has a tool for it, but few other packages do.</P><P></P><P>Doc Muhlbaier</P><P>Duke</P></BODY></HTML> Wed, 13 Jun 2012 02:09:35 GMT https://communities.sas.com/t5/Statistical-Procedures/Trouble-getting-hazard-ratio/m-p/81197#M3895 Doc_Duke 2012-06-13T02:09:35Z