156
•
•
•Where S
1
, S
2
, and S
3
are:
•
•
•
• a, b and c are determined by solving the three equations above simulta-
neously.
Forecasting With Exponential Smoothing
• a = smoothing constant (0 < a < 1)
• X
t
= actual current period usage
c
1
n
---
S
1
S
3
S
2
2
–
S
1
S
3
2S
2
–+
------------------------------------
exp=
a
b1–()S
2
S
1
–()
bb
n
1–()
2
------------------------------------------
exp=
S
1
Iny
i
ncb aln()+ln=
i1=
n
∑
=
b
n
1–
b1–
---------------
S
2
Iny
i
ncb
n1+
aln()+ln=
in1+=
2n
∑
=
b
n
1–
b1–
---------------
1
t1+
S
t
1
α
---
T
t
+=