Block 2 Revision
Averages & Quartiles

Variance & Standard Deviation

Comparative Pie Charts

Geometric Mean

Weighed Mean

Standardised Scores

Box and Whisker Plots

Cumulative Frequency Charts

Histograms

Transforming Data

Block 3 Revision
Coming next week !

The geometric mean of a set of positive data is defined as the nth root of the product of all the members of the set, where n is the number of members.The arithmetic mean is relevant any time several quantities add together to produce a total. The arithmetic mean answers the question, "if all the quantities had the same value, what would that value have to be in order to achieve the same total?"

In the same way, the geometric mean is relevant any time several quantities multiply together to produce a product. The geometric mean answers the question, "if all the quantities had the same value, what would that value have to be in order to achieve the same product?"

You can only use geometric mean for multiplicative data like percentage change.

Method:

I'm sure you'll be pleased to know that this is an easy one!

Step 1) Multiply all the values your data togther.

Step 2) Find the nth root ()

If, for some ungodly reason, you are a fan of formulae here's that as a formula:

Worked Example:

Lets say that is my raw data: 2%,3%,6%,4%,3%,1%,8%

First we add 'em all up, which gives us 27

Then we use our calculator to find the 6th root of 27 (there are 6 values in my data set).

That gives us 1.73 which is our answer.