RDA avalon
Survival-data simulation in R and Stata under one name — standard, flexible parametric, fitted-model and user-defined hazards, with competing risks and multi-state structures. The successor to survsim, in active development.
Coming
November 2026
Not yet released avalon is in build for R and Stata.
What avalon does
avalon simulates survival data from a wide range of hazard specifications — standard parametric distributions, flexible parametric (spline) models, fitted models, and fully user-defined hazard or log-hazard functions — with time-dependent effects, competing risks, multi-state structures, and left truncation. It is the workhorse the rest of the family is tested against: the known-truth data generator behind merlin, morgana, and pendragon's validation.
It is the cross-ecosystem successor to the Stata survsim package, bringing the same simulation engine to both ecosystems under one name — so a project that spans R and Stata no longer needs a different simulation package in each. simsurv (Brilleman et al.) remains the established R option and is unaffected by this.
avalon is in active development. Until it is released, survsim remains the mature, fully supported Stata simulator (on SSC today), and its design carries directly into avalon.
Simulate almost any survival process — in Stata or R
avalon carries survsim's proven simulation scope into one cross-ecosystem package. The capabilities below describe that target scope; the package is in active development.
Standard & flexible parametric
Exponential, Weibull, Gompertz, and Royston-Parmar / log-hazard spline baselines — or simulate from a fitted model.
Custom hazards
Simulate from any user-supplied hazard or log-hazard function — no closed form required.
Competing risks & multi-state
Competing-risks and multi-state data, with time-dependent effects and left truncation.
R + Stata parity
The same simulation API and behaviour in R and Stata, carried over from survsim.
Get started
avalon is in active development in both R and Stata, and is not yet on SSC or CRAN.
Available today: survsim, avalon's mature Stata predecessor, installs from SSC with ssc install survsim. Get in touch if you'd like early access to avalon.
A first model
avalon is in build. Both blocks show the intended interface, which follows survsim's where it can so that existing simulation code carries over.
Planned syntax. The blocks marked planned show the interface being built, not a command you can run today. They may change before release.
library(avalon)
# survival times from a Weibull model with a treatment effect,
# administratively censored at five years
d <- avalon(
n = 1000,
distribution = "weibull",
lambda = 0.1, gamma = 1.2,
covariates = list(trt = 0.5),
maxtime = 5
)* survival times from a Weibull model with a treatment effect,
* administratively censored at five years
avalon stime died, distribution(weibull) lambda(0.1) gamma(1.2) ///
covariates(trt 0.5) maxtime(5)The simulation workhorse
Worked examples and tutorials for the family are in our Resources.
Try it in your browser: the survival DGM explorer and the multi-state explorer — choose a data-generating mechanism interactively, then export run-ready avalon code.
Citing avalon
avalon does not have a methods paper yet — cite the software itself. It succeeds survsim; the survsim papers below describe the simulation methodology.
@misc{avalon2026,
author = {Crowther, Michael J.},
title = {{avalon: flexible simulation of survival data}},
year = {2026},
url = {https://reddooranalytics.se/software/avalon/},
note = {Red Door Analytics}
}