fix Gamma simulation (#782, still needs test)

lme4 · Apr 26, 2024 · 2ab7cc3 · 2ab7cc3
1 parent e0071b7
commit 2ab7cc3
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Showing 2 changed files with 3 additions and 2 deletions.
diff --git 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
@@ -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}{