From 2ab7cc3e1aa182b41bed37111ebf7d8541452cc8 Mon Sep 17 00:00:00 2001
From: Ben Bolker <bbolker@gmail.com>
Date: Fri, 26 Apr 2024 10:34:00 -0400
Subject: [PATCH] fix Gamma simulation (#782, still needs test)

---
 R/predict.R  | 2 +-
 inst/NEWS.Rd | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/R/predict.R b/R/predict.R
index 8ec62139..4bd2840b 100644
--- a/R/predict.R
+++ b/R/predict.R
@@ -935,7 +935,7 @@ Gamma_simfun <- function(object, nsim, ftd=fitted(object),
     if (any(wts != 1)) message("using weights to scale shape parameter")
     ## used to use gamma.shape(), but sigma() is more general
     ## (wouldn't work *outside* of the merMod context though)
-    shape <- sigma(object)*wts
+    shape <- 1/sigma(object)^2*wts
     rgamma(nsim*length(ftd), shape = shape, rate = shape/ftd)
 }
 
diff --git a/inst/NEWS.Rd b/inst/NEWS.Rd
index 6e8e0b56..9a663754 100644
--- a/inst/NEWS.Rd
+++ b/inst/NEWS.Rd
@@ -9,9 +9,10 @@
     \itemize{
       \item \code{predict(., re.form=...)} works in a wider range of
       cases (GH #691)
+      \item Gamma simulation now uses correct shape parameter (GH #782)
     }
   } % bug fixes
-} % 1.1-35.3
+} % 1.1-35.9000
   
 \section{CHANGES IN VERSION 1.1-35.3 (2024-04-16)}{
   \subsection{BUG FIXES}{