sd                   package:stats                   R Documentation

Standard Deviation

Description:

     This function computes the standard deviation of the values in
     'x'. If 'na.rm' is 'TRUE' then missing values are removed before
     computation proceeds. If 'x' is a matrix or a data frame, a vector
     of the standard deviation of the columns is returned.

Usage:

     sd(x, na.rm = FALSE)

Arguments:

       x: a numeric vector, matrix or data frame. An object which is
          not a vector, matrix or data frame is coerced (if possible)
          by 'as.vector'.

   na.rm: logical. Should missing values be removed?

Details:

     Like 'var' this uses denominator n - 1.

     The standard deviation of a zero-length vector (after removal of
     'NA's if 'na.rm = TRUE') is not defined and gives an error. The
     standard deviation of a length-one vector is 'NA'.

See Also:

     'var' for its square, and 'mad', the most robust alternative.

Examples:

     sd(1:2) ^ 2

