Author note — to cover

Identify outliers informally as values far from the pattern, in lists and on scatter graphs; decide whether to exclude one as an error or keep it as genuine, and state its effect on the mean, median, mode and range. No quartile-based rule: the 1.5 times IQR test is A level. Both tiers. (S4)

Introduction

—coming soon—

Practice and continue

Practice

Outliers

Spotting a value far from the rest, and whether it is an error or genuine.

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Comparing data sets with an average and the range

A fair comparison pairs an average with a measure of spread, both in context.