diff --git a/R/accuracy.R b/R/accuracy.R
index 6efeb95324ea665cf6660d4685af491372614b00..887c1e8a971f7c61363737cebd8d21144aa00a15 100644
--- a/R/accuracy.R
+++ b/R/accuracy.R
@@ -210,7 +210,8 @@ accuracy.DataFrameStack <- function(x, observed,
 #' @family accuracy functions
 mean.accuracy = function(x, ...){
   aux = x$accuracy - x$p
-  mean(ifelse(aux>0,1,0),...)
+  n = nrow(x)
+  n/(n-1)*mean(ifelse(aux>0,1,0),...)
 }
 
 
@@ -250,8 +251,9 @@ precision <- function(x,...) UseMethod("precision",x)
 #' @export
 precision.accuracy <- function(x, ...){
   aux = x$accuracy - x$p
-  erg = c(precision=1-2* x$accuracy %*% ifelse(aux>0,aux,0),
-      goodness = 1-(3*x$accuracy-2) %*% aux)/nrow(x)
+  a = ifelse(aux>0,1,0)
+  erg = c(precision=1-2*(a %*% aux)/(nrow(x)-1),
+      goodness = 1-((3*a-2) %*% aux)/(nrow(x)-1))
   return(erg)
 }