alt Hacker NewsAs a number of the comments have suggested there are a number of Monte Carlo methods (including this addin) but I was hoping that someone would make one which calculated based on random variables and output a resultant random variable, over brute force monte carlo. Monte Carlo is also somewhat slow, but doing the maths analytically should be fast.
MC is used because there is no analytic solution. Only some likelihood functions have a conjugate prior. You have to rework the analytic solution for every model change (where most changes would result it in being non-analytic anyway), and they don't work well for high dimensional problems. Restricting the tool to analytic would mostly result in a toy app that just does Gaussians.