fix: beta-binomial numerical instability

storopoli · Dec 3, 2023 · 23ec89d · 23ec89d
1 parent e23bf1b
commit 23ec89d
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/turing/07-robust_beta_binomial_regression-wells.jl b/turing/07-robust_beta_binomial_regression-wells.jl
@@ -24,7 +24,8 @@ X = standardize(ZScoreTransform, X; dims=1)
 y = wells[:, :switch]
 
 # define alternate parameterizations
-BetaBinomial2(n, μ, ϕ) = BetaBinomial(n, μ * ϕ, (1 - μ) * ϕ)
+# eps() for numerical stability
+BetaBinomial2(n, μ, ϕ) = BetaBinomial(n, μ * ϕ, max((1 - μ) * ϕ, eps()))
 
 # define the model
 @model function beta_binomial_regression(X, y; predictors=size(X, 2))