FRAME 33.
MEASURES OF DISPERSION
Now we will discuss two measures of dispersion. As indicated earlier, dispersion measures
the spread or variability of the data about the mean value. The measures of central tendency
provide significant information about a group of data. In most cases, however, more information
is needed. It is the combination of measures of central tendency and measures of dispersion
that provide a clearer description or summary of the data.
The following example illustrates that a measure of dispersion provides important additional
information about a group of observations.
ANNUAL WAGES OF TWO GROUPS OF WORKERS
Group A
Group B
$ 1,000
$ 2,500
1,275
2,775
1,325
2,800
1,350
2,850
1,475
2,875
1,525
3,025
2,325
3,175
2,475
3,225
2,575
Median
3,275
3,450
and
3,450
3,825
Mean
3,700
4,025
3,725
4,425
3,775
4,475
3,875
4,525
3,950
4,550
4,000
4,575
4,025
6,375
4,050
10,000
4,500
QUESTION:
How do the two groups differ?
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