The Scottish Government

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Footnotes

1. Median is a measure of central tendency. The median of a sample is the value for which one-half (50%) of the observations (when ranked) will lie above that value and one-half will lie below that value.
2. The tables were derived from a previous survey of 11,500 motorcyclists, where overall accident risk was modelled as a function of age, mileage and experience (Sexton et al, 2004b).
3. The tables were derived from a previous survey of 11,500 motorcyclists, where accident risk was modelled as a function of age, mileage and experience (Sexton et al, 2004b).
4. In general, the k-means method will produce exactly k different clusters of greatest possible distinction. You "tell" the computer package to form exactly k clusters that are to be as distinct as possible. The best number of clusters k leading to the greatest separation (distance) is not known a priori and must be determined from the data or other information.

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