Add standard error of the mean

1 files changed, 4 insertions, 2 deletions

diff --git a/stddev.cpp b/stddev.cpp
index 5f4c8a7..b652b8a 100644
--- a/stddev.cpp
+++ b/stddev.cpp
@@ -40,8 +40,10 @@ int main(int,char **argv){
 		total+=(v-s_mean)*(v-s_mean);
 	}
 	const double s_stddev=data.size()==1?nan(""):sqrt(total/(data.size()-1));
+	const double s_stderr=s_stddev/sqrt(data.size());
 
-	cout<<"Mean:   "<<s_mean<<endl
-	    <<"Stddev: "<<s_stddev<<endl
+	cout<<"Mean:   "<<s_mean<<'\n'
+	    <<"Stddev: "<<s_stddev<<'\n'
+	    <<"Stderr: "<<s_stderr<<'\n'
 	    <<"Median: "<<s_median<<endl;
 }