Ugrás a tartalomhoz

SOCIAL STATISTICS

Renáta Németh, Dávid Simon

ELTE

Interquartile range

Interquartile range

but

is based on the maximum and minimum values only, hence it is sensitive to the outliers.

Interquartile range (IQR) is introduced to avoid this instability:

IQR is defined as the difference between the lower and upper quartiles.

Appropriate for interval-ratio variables. (The case of ordinal variables will be discussed later).

Back to the previous example:

Party preference

1. quartile

3. quartile

IQR

Range

MDF

74250

500000

425.750

457.000

SZDSZ

50750

112500

61.750

476.000

FKGP

47500

68500

21.000

30.000

MSZP

53000

95000

42.000

490.000

FIDESZ

44500

90000

45.500

485.000

Munkáspárt

49100

113750

64.650

87.600

MIÉP

32851

396250

363.399

477.000

Other

56500

218750

162.250

446.000

Uncertain

46000

110000

64.000

498.000

Total

49.250

100.000

50.750

498.000

Check the computation of the IQR by comparing the 3. and 1. quartiles.

Interpret the IQRs!

When variability was measured by the range, uncertain voters showed the highest variability. Has this conclusion changed? How could you explain the change?

Example

Range or IQR? Number of cars within two groups of people.