This document defines and provides formulas for kurtosis, a statistical measure of the peakedness of a distribution curve. Kurtosis values indicate whether a curve is normal/mesokurtic (Ku=0.263), flat/platykurtic (Ku>0.263), or thin/leptokurtic (Ku<0.263). It also includes an example frequency distribution of examination marks in statistics.

1. KURTOSIS

2. Kurtosis
-the degree of peakedness or flatness of a curve
called kurtosis, denoted by Ku. This is also known
as percentile coefficient of kurtosis and its formula is
given by
QD
PR
KU 
where QD = quartile deviation
PR = percentile range

3. When the Ku is:
a. Equal to 0.263, the curve is a normal
curve or mesokurtic
b. Greater than 0.263, the curve is platykurtic or flat
c. Less than 0.263, the curve is leptokurtic or thin.

4. Frequency Distribution of Examination Marks in Statistics
Scores f x fx <CF
Class Boundaries
Lower Upper
90-94 1 92 92 60 89.5 94.5
85-89 4 87 348 59 84.5 89.5
80-84 3 82 246 55 79.5 84.5
75-79 8 77 616 52 74.5 79.5
70-74 20 72 1,440 44 69.5 74.5
65-69 15 67 1,005 24 64.5 69.5
60-64 7 62 434 9 59.5 64.5
55-59 1 57 57 2 54.5 59.5
50-54 1 52 52 1 49.5 54.5
N= 60 4, 290