# weighted.mean

0th

Percentile

##### Weighted Arithmetic Mean

Compute a weighted mean.

Keywords
univar
##### Usage
weighted.mean(x, w, ...)
"weighted.mean"(x, w, ..., na.rm = FALSE)
##### Arguments
x
an object containing the values whose weighted mean is to be computed.
w
a numerical vector of weights the same length as x giving the weights to use for elements of x.
...
arguments to be passed to or from methods.
na.rm
a logical value indicating whether NA values in x should be stripped before the computation proceeds.
##### Details

This is a generic function and methods can be defined for the first argument x: apart from the default methods there are methods for the date-time classes "POSIXct", "POSIXlt", "difftime" and "Date". The default method will work for any numeric-like object for which [, multiplication, division and sum have suitable methods, including complex vectors.

If w is missing then all elements of x are given the same weight, otherwise the weights coerced to numeric by as.numeric and normalized to sum to one (if possible: if their sum is zero or infinite the value is likely to be NaN).

Missing values in w are not handled specially and so give a missing value as the result. However, zero weights are handled specially and the corresponding x values are omitted from the sum.

##### Value

For the default method, a length-one numeric vector.

mean
library(stats) ## GPA from Siegel 1994 wt <- c(5, 5, 4, 1)/15 x <- c(3.7,3.3,3.5,2.8) xm <- weighted.mean(x, wt)