fdth (version 1.2-1)

var: Variance of frequency distribution table (numerical variable)

Description

S3 methods for the variance of a fdt. Useful to estimate the variance (when the real data vector is not known) from a previous fdt.

Usage

## S3 generic
var(x, ...)
## S3 methods: numerical
"var"(x, ...)
"var"(x, ...)
"var"(x, ...)

Arguments

x

A fdt (simple or multiple) object.

...

Required to be generic.

Value

returns a numeric vector containing the value of the median of the fdt. median.fdt.multiple returns a list, where each element is a numeric vector containing the value of the variance of the fdt for each variable.

Details

var.fdt calculates the value of the variance based on a known formula. var.fdt.multiple calls var.fdtfor each variable, that is, each column of the data.frame.

See Also

sd.fdt, mean.fdt.

Examples

mdf <- data.frame(x=rnorm(1e2, 
                          20, 
                          2),
                  y=rnorm(1e2, 
                          30,
                          3),
                  z=rnorm(1e2,
                          40,
                          4))

head(mdf)

apply(mdf,
      2,
      var)

var(fdt(mdf))