I am doing a proportional hazards model and trying to do a bootstrap for the risk ratios. I can't provide my data, but since I keep getting the same error in both my data and a simple JMP example for the sample data library, I am attaching that example here. I run the proportional hazards model, focusing on the risk ratios for two groups (which I set up at random) - a test group and a control group. I click on the risk ratio estimates and attempt a bootstrap analysis - but I keep getting the error that it failed to converge. I understand generally what the bootstrap sample is doing and that nonconvergence is a possibility, but since I get this error every time - and with any data I try it with - I suspect I am doing something wrong. Please let me know if you can see a reason why my bootstrap keeps failing. Thank you.
SORRY! The file I attached was faulty - I created a random grouping (control/test group) that happened to contain no censored data so the hazard model was nonsense. Attached is a revised one that works. I still get the error that it could not converge, so I still have my original question about what I am doing wrong. But the attached file at least has sensible data.
The fractional weights works, at least on the sample data set I provided. I don't completely understand the reason - the data I am really using is a much larger dataset so your explanation about sparse cells seems unlikely to me (though it applies to the small sample data set I provided). I'll try it on my other data now, but for the time being your solution works!