diff --git a/R/sem.R b/R/sem.R
new file mode 100644
index 0000000..795ec06
--- /dev/null
+++ b/R/sem.R
@@ -0,0 +1,4 @@
+sem <- function(x, na.rm=F){
+  sem<-sd(x, na.rm = na.rm)/sqrt(length(x))
+  return(sem)
+}
diff --git a/man/sem.Rd b/man/sem.Rd
new file mode 100644
index 0000000..862871b
--- /dev/null
+++ b/man/sem.Rd
@@ -0,0 +1,17 @@
+\name{sem}
+\alias{sem}
+\title{sem}
+\usage{
+sem(x, na.rm=T)
+}
+\arguments{
+  \item{x}{A numeric vector or an R object but not a factor coercible to numeric by as.double(x).}
+  \item{na.rm}{A logical value indicating whether NA values should be stripped before the computation proceeds.}
+}
+\description{
+This function computes the Standard Error of the Mean of the values in x. If na.rm is TRUE then missing values are removed before computation proceeds.
+}
+\examples{
+v<-rnorm(10)
+sem(v)
+}