
212 Empirical Research in Software Engineering
The IQR is dened as the difference between upper quartile and lower quartile and is given as,
For example, for Table6.5,the quartiles are shown in Figure6.4.
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The standard deviation is used to measure the average distance a data point has from the
mean. The standard deviation assesses the spread by calculating the distance of the data
point from the mean. The standard deviation is large, if most of the data points are near to
the mean. The standard deviation (σ
x
) for the population is given as:
σ
µ
x
x
N
=
−
∑
2
where:
x is the given value
N is the number of values
µ is ...