1. 8-2 Measures of Central Tendency and Range

2. Measure of Central Tendency  A number used to describe the center of a set of data  Mean, Median, Mode

3. 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

4. Mode  The number that occurs most often.  Mode = most often

5. Mode examples???  No mode  One mode  Two modes

6. Median Highway 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

7. Range  Is a “measure of variation”  Difference between the least and greatest values

8. 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