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Reply To: Using a Weibull distribution in St-Sim

Syncrosim Forums ST-Sim & State-and-Transition Simulation Models Using a Weibull distribution in St-Sim Reply To: Using a Weibull distribution in St-Sim

#21960
leonardo-fridleonardo-frid
Keymaster

Hi Kori,

I am curious as to why you want to sample from a Weibull distribution for transition probabilities? A Weibull is typically used to model time to failure, with an example of this being fire return intervals, not probabilities. Outputs of single cell ST-Sim runs using fixed probabilities that are either constant or vary with age will produce different shapes of a Weibull distribution for the times between transition events on that cell. A constant probability that does not vary with age will produce an exponential distribution for times between transition events. An exponential distribution is just a special case of the Weibull.

Built in distribution support in SyncroSim currently includes (Beta, Gamma, Normal, Uniform and Uniform Integer), but not Weibull. This is something we could consider adding.

In the meantime, if you still want to sample from a Weibull, you could do your own sampling outside of SyncroSim to generate a datasheet for multipliers where the following fields are specified:
1. Iteration [only required if you want every iteration to be different]
2. Timestep
3. Transition Group [the transition group that you want to vary probabilities for]
4. Multiplier [sampled from your Weibull distribution]

To sample from a Weibull you could use R:
https://search.r-project.org/CRAN/refmans/distributions3/html/random.Weibull.html

Cheers,
Leonardo