HP 12C#ABA hp 12c_solutions handbook_English_E.pdf - Page 157
Forecasting With Exponential Smoothing, Where
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• c = exp 1-n -S----1S----+-1---S-S---3-3---------S--2---22S-----2- • a = exp (---b----------1----)--(---S----2----------S----1---) b(bn - 2 1) • Where S1, S2, and S3 are: • 1t + 1 = St + α-1-- Tt n ∑ S1 = Inyi = n lnc + b( ln a) b--b--n---------1--1- i=1 • 2n ∑ S2 = Inyi = n ln c + bn + 1( ln a) -b-b--n---------1--1- i = n+1 • • a, b and c are determined by solving the three equations above simulta- neously. Forecasting With Exponential Smoothing • a = smoothing constant (0 < a < 1) • Xt = actual current period usage 156
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
b
1
–
(
)
S
2
S
1
–
(
)
bb
n
1
–
(
)
2
-----------------------------------------
exp
=
S
1
Iny
i
n
c
b
a
ln
(
)
+
ln
=
i
1
=
n
∑
=
b
n
1
–
b
1
–
--------------
S
2
Iny
i
n
c
b
n
1
+
a
ln
(
)
+
ln
=
i
n
1
+
=
2n
∑
=
b
n
1
–
b
1
–
--------------
t
1
+
S
t
1
α
---
T
t
+
=