Page 43 - MATLAB Recipes for Earth Sciences

34 3 Univariate Statistics

Negative Skewness Positive Skewness
40 40
35 35
30 30
25 25
f(x) 20 f(x) 20
15 15
10 10
5 5
0 0
−2 0 2 4 6 8 −2 0 2 4 6 8
x x
a b
High Kurtosis Low Kurtosis
80
100
70
80 60
50
60
f(x) f(x) 40
40 30
20
20
10
0 0
0 10 20 30 6 8 10 12 14 16 18
x x
c d
Bimodal Distribution Trimodal Distribution
80 60
Mode 1 Mode 2 Mode 2 Mode 3
70
50
60 Mode 1
40
50
f(x) 40 f(x) 30
30
20
20
10
10
0 0
10 15 20 5 10 15 20
x x
e f
Fig. 3.3 Dispersion and shape of a distribution. a-b Unimodal distributions showing a
negative or positive skew. c-d Distributions showing a high or low kurtosis. e-f Bimodal and
trimodal distribution showing two or three modes.