diff --git a/src/ML/Likelihoods/negbin.jl b/src/ML/Likelihoods/negbin.jl
index e832630..aa4516a 100644
--- a/src/ML/Likelihoods/negbin.jl
+++ b/src/ML/Likelihoods/negbin.jl
@@ -9,8 +9,8 @@ function  negbin(θ, y, x, nbtype)
     eps = 1e-8 
     λ = eps .+ exp.(x*β)
     α = eps .+ exp(θ[end])
-    nbtype == 1 ? r = λ./α : r = ones(n)/α
-    p = r ./ (r + λ)
+    nbtype == 1 ? ψ  = λ./α : ψ  = ones(n)/α
+    p = ψ  ./ (ψ  + λ)
     all(r .> 0.0) & all(p .> 0.0) & all(p .< 1.0) ? log.(pdf.(NegativeBinomial.(r, p),y)) : -Inf    
 end