Estimation of In Situ pH on PM 2.5 in Hong Kong Using Online Ionic ...

Testing the predicting capability <strong>of</strong> the
linear regression equation
Approach: First, use randomly selected 90% <strong>of</strong> the cases to
obtain a regression equation; Then the regression equation
is used to predict the <strong>pH</strong> IS
for the remaining 10% cases.
<strong>pH</strong> IS
= .91R
+
+ 3.13 RH 5.70 <strong>pH</strong> IS
= .96R
+
+ 3.11RH
5. 72 = .97R
+
+ 3.10 RH 5. 72
4
/-
−
4
/-
−
<strong>pH</strong> IS
4
/-
−
by
2
1
y=0.99x-0.01
y = - 0.01
R 2 =0.94
R 2 = 0.94
0
-1
-2
-3
-3 -2 -1 0 1 2
2
1
y=1.02x-0.02
y = - 0.02
R 2 =0.92 R 2 = 0.92
0
-1
-2
-3
-2 -1 0 1 2
By model output
2
1
y=1.05x+0.02
y = + 0.02
R 2 =0.91 R 2 = 0.91
0
-1
-2
-2 -1 0 1 2
18