R: Weighted mean, variance and standard deviation calculations

wt.mean {SDMTools} | R Documentation

## Weighted mean, variance and standard deviation calculations

### Description

`wt.mean` calculates the mean given a weighting of the values.
`wt.var` is the unbiased variance of the weighted mean calculation using equations of GNU Scentific Library (http://www.gnu.org/software/gsl/manual/html_node/Weighted-Samples.htmland.
`wt.sd` is the standard deviation of the weighted mean calculated as the sqrt of `wt.var`.
Note: NA data is automatically ommitted from analysis.

### Usage

    wt.mean(x, wt)

    wt.var(x, wt)

    wt.sd(x, wt)

### Arguments

`x` | is a vector of numerical data.
`wt` | is a vector of equal length to `x` representing the weights.)

### Value

returns a single value from analysis requested.

### Author(s)

Jeremy VanDerWal jjvanderwal@gmail.com

### Examples

    #define simple data
    x = 1:25 # set of numbers
    wt = runif(25) #some arbitrary weights

    #display means & variances (unweighted and then weighted)
    mean(x); wt.mean(x,wt)
    var(x); wt.var(x,wt)
    sd(x); wt.sd(x,wt)

[Package SDMTools version 1.1-221.2 Index]