1
Index of qualitative variation IQV
IQV =
K (100
2

Σ
f
2
)
100
2
(K1)
K
= the number of categories
Σ
f
2
= the sum of all squared frequencies or percentages
#1 pg 162 6
th
edition
Political Views
Percent
Percent
Squared
Extremely Liberal
3.6
12.96
Liberal
12.2
148.84
Slightly Liberal
12.0
144
Moderate
38.0
1444
Slightly
Conservative
14.1
198.81
Conservative
16.8
282.24
Extremely
Conservative
3.3
10.89
Total
100.00
2241.74
Sum of Percents
Squared
Insert 2241.74 into
formula above
IQV=0.91 Close to
1.00 therefore
political views are
diverse.
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2
Calculating IQR, Variance and Standard Deviation
IQR
is the distance between the values at the 25
th
percentile and the 75
th
Percentile. Rank order your data. Locate
the value for the case that marks the 25
th
percentile (Q1) and the value that marks the 75
th
percentile (Q3). Subtract
to calculate the distance Q3Q1= IQR
Standard deviation is the square root of the Variance.
The formula for the
Variance
is:
The formula for
Standard Deviation
is:
Examples using age data for two classes. This is raw data, not a frequency table.
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 Spring '11
 Heberle
 Standard Deviation, Variance, Statistical dispersion

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