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can be used to provide a graphical display of center and variation of a data set. Like Stem and
Leaf diagrams, invented by John Tukey (1915-2000).
To construct a box plot (see pp. 120-121):
1. Determine the quartiles. 23, 30.5 and 36.5
2. Determine potential outliers and adjacent values. TV viewing times example are 5 and 43
3. Draw a horizontal axis mark the quartiles and adjacent values (scale start and end pointswhiskers mark the start and end points of the scale). TV viewing times range from 5 to
66 so place whiskers at 0 and 70.
4. Connect the quartiles to make a box and then to the adjacent lines
5. Plot each potential outlier with an asterisk; From TV viewing times example, 66 is
Comparing Data Sets by Using Box Plots – (1) compare range of values, i.e. center and
variation; (2) also distribution of data set 3.4 Descriptive Measures for Populations
The Population Mean
Recall Sample Mean x = Size
Sample n Population N Mean
̅ many means (depending upon number of samples)
one mean (finite population) Population Mean of a Variable - mean of observation f...
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This document was uploaded on 02/06/2014.
- Spring '14