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Weighted Mean Calculation Guide

The weighted mean formula is Σwx/Σw, where w represents the weights, x represents the values, Σwx is the sum of multiplying each value by its corresponding weight, and Σw is the sum of all the weights. To calculate the weighted mean: 1) multiply each value by its weight, 2) sum the results, 3) sum all the weights, and 4) divide the sum from step 2 by the sum from step 3. If the weights do not sum to 1, you must divide the sum of weighted values by the total of the weights.

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3K views1 page

Weighted Mean Calculation Guide

The weighted mean formula is Σwx/Σw, where w represents the weights, x represents the values, Σwx is the sum of multiplying each value by its corresponding weight, and Σw is the sum of all the weights. To calculate the weighted mean: 1) multiply each value by its weight, 2) sum the results, 3) sum all the weights, and 4) divide the sum from step 2 by the sum from step 3. If the weights do not sum to 1, you must divide the sum of weighted values by the total of the weights.

Uploaded by

Mich Elbir
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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Weighted mean = Σwx/Σw

 Multiply the numbers in your data set by the weights.


 Add the numbers in Step 1 up. Set this number aside for a moment.
 Add up all of the weights.
 Divide the numbers you found in Step 2 by the number you found in Step 3.

Weighted Mean: Formula: How t

Weighted Mean Formula


The weighted mean is relatively easy to find. But in some cases the weights might not add up to 1. In
those cases, you’ll need to use the weighted mean formula. The only difference between the formula and
the steps above is that you divide by the sum of all the weights.

The image above is the technical formula for the weighted mean. In simple terms, the formula can be
written as:
Weighted mean = Σwx/Σw
Σ = the sum of (in other words…add them up!).
w = the weights.
x = the value.
To use the formula:

1. Multiply the numbers in your data set by the weights.


2. Add the numbers in Step 1 up. Set this number aside for a moment.
3. Add up all of the weights.
4. Divide the numbers you found in Step 2 by the number you found in Step 3.
In the sample grades problem above, all of the weights add up to 1 (.4 + .4 + .2) so you would divide your
answer (83) by 1:
83 / 1 = 83.
However, let’s say your weighted means added up to 1.2 instead of 1. You’d divide 83 by 1.2 to get:
83 / 1.2 = 69.17.
Warning: The weighted mean can be easily influenced by outliers in your data. If you have very high or
very low values in your data set, the weighted mean may not be a good statistic to rely on.

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