# What is the scenario where we need to use weighted mean

#1

Hello,

At times we use weighted mean instead of simple means.Which are the typical business scenarios im which a weighted mean is more preferred rather than the simple mean.
I would be grateful if someone can explain with an example!!

#2

Hi

weighted.mean {stats}

Weighted Arithmetic Mean

Description

Compute a weighted mean.

Usage
weighted.mean(x, w, …)

## Default S3 method:

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

Examples

## 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)

Hope this helps.

thnks
tony