How we change what others think, feel, believe and do

Median

A measure of the center point of a set of numerical data. It may be used in situations such as when have scored a number of suppliers on their capability and want to know which 50% are the best.

The median can be found by sorting the numbers into numeric order and selecting the middle number. If there are an even number of numbers, then the average of the middle two numbers is used. Thus the median of 1 2 4 5 6 is 4, and the median of 1 2 4 5 is 3.

The advantage of the median is that it is not affected by outlier numbers (like 256 in the lists above). However, it is only one number and does not take the value of the other numbers into account.

Whilst the Median gives a measure of central tendency, the common method of measuring the spread of a set of numbers is the Standard Deviation.

Other methods of measuring central tendency are Mean (or Average) and Mode.

Mean, Mode, Standard Distribution

Toolbook chapter: Variation

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