Page 138 - Computational Statistics Handbook with MATLAB

Chapter 5: Exploratory Data Analysis 125

3

2
Standard Normal Quantiles −1

1

0

−2

−3
−3 −2 −1 0 1 2 3 4
Sorted Data
IG
FI F U URE G 5. RE 5. 9 9
GU
9
F F II GU RE RE 5. 5. 9
This is a quantile plot or normal probability plot of a random sample generated from a
standard normal distribution. Note that the points approximately follow a straight line,
indicating that the normal distribution is a reasonable model for the sample.
3
2
Standard Normal Quantiles −1
1

0

−2

−3
0 0.2 0.4 0.6 0.8 1
Sorted Data

II
U
F FI F F IG URE G 5.10 RE RE RE 5.10
GU
5.10
5.10
GU
Here we have a quantile plot where the sample is generated from a uniform distribution,
and the theoretical quantiles are from the normal distribution. The shape of the curve verifies
that the sample is not from a normal distribution.
© 2002 by Chapman & Hall/CRC