Compute the standard error of the mean (SEM). The SEM is the standard deviation of the sample-mean's estimate of a population mean.
It therefore describes the accuracy of the calculation of a sample's mean.
If na.rm is TRUE then missing values are removed before computation proceeds.
Usage
sem(x, na.rm = FALSE)
Value
A numeric scalar -- the standard error of the mean.
Arguments
x
a numeric vector
na.rm
logical. Should missing values be removed?
Details
The SEM of a zero-length vector (after removal of NAs if na.rm = TRUE) is not defined and gives an error.
The SEM of a length-one vector is NA.