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8-2 Measures of Central Tendency and Range. Measure of Central Tendency. A number used to describe the center of a set of data. Mean, Median, Mode. Mean. The sum of the data divided by the number of items in the set “average” The average teacher is Mean
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Measure of Central Tendency • A number used to describe the center of a set of data • Mean, Median, Mode
Mean • The sum of the data divided by the number of items in the set • “average” The average teacher is Mean • Ex: 1 cm, 1 cm, 5 cm, 2 cm, 2 cm, 4 cm, 2 cm, 5 cm
Mode • The number that occurs most often. • Mode = most often
Mode examples??? • No mode • One mode • Two modes
MedianHighway medians are in the middle. • After the data set has been ordered least to greatest, it is the middle number or the mean(average) of the two middle numbers • Ex: 15 yd, 7 yd, 20 yd, 17 yd, 11 yd, 20 yd
Range • Is a “measure of variation” • Difference between the least and greatest values
When to use what??? • Mean- when data has no outliers • Median- when data has outliers and there are no big gaps in the middle of the data • Mode- data has many identical numbers • Range- to describe the spread of data