Selecting The "Best" Smoothing Constant - HP 12c Solutions Handbook

6
n: Unused
PV: Unused
FV: Unused
R : 1-
1
R : T
3 t-1
R : D
5 t
R -R : Unused
7 .4

Selecting the "best" smoothing constant ( ):

1. Key in the program and press
2. Key in the number 1 and press
3. Key in the "trial " and press
4. Key in the first historical value (X
5. Key in the second historical value (X
result is the error between the forecast value (
(X )
t+1
6. Press
7. Optional: Press
demand.
8. Continue steps 5 and 6 for X
been entered. When doing step 5 merely key in the value and press
(do not press
9. Press
2
( e ). Record the value and the following additional values; press
( ),
(forecast
10. Press
11. Repeat steps 2 through 10 until a "best"
cumulative forecasting error (Register 4).
Forecasting:
00
REGISTERS
; the display shows the next forecast (
5 to display the smoothed estimate of current
6).
4. This value represents the cumulative forecasting error
2 (smoothed average S
).
t+1
CLEAR .
42- 44
43-43, 33
i: Unused
PMT: Unused
R :
0
R : S
2 t-1
2
R : e
4
R :
6 t+1
CLEAR
.
0
) and press
1
) and press
2
, X , ... X until all historical values have
3 4 n
), 3 (trend T
t-1
is selected based on the lowest
90
6
00
.
1.
2.
6 . The
) and the true value
t+1
).
t+2
) and
t-1
0
6