Help with modelling rstanarm model in brms
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- R
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Description
We are trying to fit a hierarchical bayesian survival model with a site-specific intercept and a site-specific coefficient for the covariate trt (i.e. treatment) using the brms and rstanarm packages. In rstanarm the model formulation for this is: formula = Surv(eventtime, status) ~ trt + (trt | site). We have tried several formulations in brms and are able to match the estimates however our credible intervals are completely different. This is whilst using the same priors, seed, chains, cores, iterations and adapt delta specifications. Can anyone tell us how to model the above rstanarm model in brms? Many thanks in advance
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Research direction
Start by comparing the stated rstanarm formula, Surv(eventtime, status) ~ trt + (trt | site), with the attempted brms formulations and the shared sampling settings. Reproduce the differing credible intervals, then determine whether the discrepancy comes from the model specification or package behavior and document the matching brms formulation.
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Assessment
- Tech stack
- r
- Domain
- machine-learning
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100