wt.mean: Weighted mean, variance and standard deviation calculations

In SDMTools: Species Distribution Modelling Tools: Tools for processing data associated with species distribution modelling exercises

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 [e-mail]

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)

Example output

[1] 13
[1] 14.25894
[1] 54.16667
[1] 51.16681
[1] 7.359801
[1] 7.153098

SDMTools documentation built on Jan. 11, 2020, 9:23 a.m.