Hi
I have a question regarding selection of covariates for survival analysis. I have a data set from a cohort study, following a group of dogs exposed to antimicrobials for the occurrence of resistance- measuring antimicrobial resistance to specific antimicrobials at 6 discreet time intervals. My concern at the moment is that I have very small sample sizes in each of the antimicrobial cohort group. The sample size in my largest group is 39 dogs and my smallest cohort has 9 dogs. Are there any guidelines in how many covariates I can consider when doing a survival analysis even at the univariate stage (like there are for linear and logistic regression). There is a lot data available on these dogs, but given the very small sample sizes, I feel that I need to be very prudent in covariate selection for univariate and multivariable analysis.
Thanks
Colleen
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
