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    <p>Simple, </p> <ol> <li>multiply each of the 4 values by their weight</li> <li>add the results together</li> <li>divide by the sum of the weights</li> </ol> <h3>Examples</h3> <ul> <li><p>In the example each of the fields can be thought to have an equal weight of 1</p> <pre><code>((0.12 * 1) + (0.67 * 1) + (1.00 * 1) + (0.93 * 1)) / 4 = 0.68 </code></pre></li> <li><p>Now if we want to make field2 worth 2x more than the other fields</p> <pre><code>// Weights are (1 + 2 + 1 + 1) = 5 ((0.12 * 1) + (0.67 * 2) + (1.00 * 1) + (0.93 * 1)) / 5 = 0.678 </code></pre></li> <li><p>If we want field 3 to have 100 times the weight (field 2 is still 2x)</p> <pre><code>// Weights are (1 + 2 + 100 + 1) = 104 ((0.12 * 1) + (0.67 * 2) + (1.00 * 100) + (0.93 * 1)) / 104 = 0.9845192307692308 </code></pre></li> </ul> <h3>Formula</h3> <pre><code>((field1 * field1_weight) + (field2 * field2_weight) + ... + (fieldn * fieldn_weight)) / (field1_weight + field2_weight + ... + fieldn_weight) = weighted_average </code></pre> <h3>Fractional weights</h3> <p>The formula works just the same if you give fractions as weights. For example if you would like the weight of the 4th field to be weighted <code>150%</code> more then the other fields you can assign it weight <code>1.5</code></p> <pre><code>// Weights are (1 + 1 + 1 + 1.5) = 4.5 ((0.12 * 1) + (0.67 * 1) + (1.00 * 1) + (0.93 * 1.5)) / 4.5 = 0.7077777777777778 </code></pre> <h3>Weights are relative</h3> <p>You don't need to start with each of the weights set to 1, you can use 100 or 1000 if you like.</p> <p>For example if the weights for all 4 fields were 100 the final average would be the same if they were all 1.</p> <h3>Further reading</h3> <p><a href="http://en.wikipedia.org/wiki/Weighted_arithmetic_mean" rel="noreferrer">wikipedia: Weighted arithmetic mean</a></p>
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    1. COawesome explanation with examples! thanks +1
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