We have used stemplots to organise and display data
sets. However, stemplots do not provide enough information about the
data. So, we use the range, mean,
median, mode,
quartiles and
interquartile range to obtain additional information concerning the
data. Then a boxplot is drawn to display the range, interquartile
range, lower quartile, upper quartile and the median of the data set.
Range
Range is defined as the difference between the highest and lowest
scores. That is:
Range = Highest score –
Lowest score
Example 7
Find the range of the following data set:
7 3
12 34 62
Solution:
Note:
-
Range is a measure of spread and it tells us how much a data
set is spread out or scattered.
-
The mean, median
and mode are called the measures of central
tendency because these give us an indication of the middle value
around which a set of values have a tendency to cluster.
Key Terms
range, measure of spread
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