−0.15 −0.1 −0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
−0.15
−0.1
−0.05
0
0.05
0.1
Scores on PC 1 − 65.3 %
Scores on PC 2 − 13.4 %
−50
0
50
100
150
200
250
300
350
−20
0
20
40
60
80
Scores on PC 1 − 94.1 %
Scores on PC 2 − 4.3 %
E1
E2
E3
E4
E5
R6
R7
R8
R9
R10
R11
R12
R13
R14
W16
R20
R23
R24
R26
R27
(a)
(b)
Plate 15. Principal components analysis of the Horsens catchment data set showing the effect of different preprocessing methods on model scores. (a) Auto-scaling. (b) Row normalization followed by
mean centering.