Page 90 - DECO504_STATISTICAL_METHODS_IN_ECONOMICS_ENGLISH

Statistical Methods in Economics

Notes N 35
Q 1 = Size of 4 = 4 = 8.75 item
th
8.75 item which lies in 20—30 group.
th
i
Q 1 = 1 ( l + q – c ) 1
f

10
= (20 + )8.75 – 8
7
×
10 .75
= 20 +
7
= 20 + 1.07 = 21.07

×
3N 335 105
Q 3 = Size of = = = 26.25 item
th
4 4 4
26.25 item which lies in 40—50 group
th
i
Q 3 = 1 f ( l + q – c ) 3

10
= 40 + ( )26.25 – 20
10
×
10 6.25
= 40 +
10
= 40 + 6.25 = 46.25
Q– Q 1
3
Q.D. =
2
46.25 – 21.07 25.18
= = = 12.59
2 2
Q– Q
Coefficient of Q.D. = 3 1
Q + Q 1
3
46.25 – 21.07 25.18
= =
+
46.25 21.07 67.32
= 0.374
Percentile
In statistics, a percentile (or centile) is the value of a variable below which a certain percent of
observations fall. For example, the 20 percentile is the value (or score) below which 20 percent of the
th
observations may be found. The term percentile and the related term percentile rank are often used
in the reporting of scores from norm-referenced tests. For example, if a score is in the 86 percentile,
th
it is higher than 85% of the other scores.
th
th
The 25 percentile is also known as the first quartile (Q ), the 50 percentile as the median or second
1
quartile (Q ), the 75 percentile as the third quartile (Q ).
th
2 3

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