HP 12C Solutions Handbook

92
The procedure is repeated for several α's.
Smoothing Constant (α) .5 .1 .25 .2
Cumulative Error (Σe
2
) 23.61 25.14 17.01 18.03
For the selected α = .25 S
t+1
= 24.28
T
t-1
= 0.34
D
t+1
= 25.64
Forecasting:
Note: At least 4 periods of current data should be entered before
forecasting is attempted.
4
23.61
Cumulative error (Σe
2
).
0
0.50 Smoothing constant (a).
2
25.11
Smoothing average (S
t-1
).
3
0.42
Trend (T
t-1
).
6
25.95
Last forecast (D
t+1
).
Keystrokes Display
CLEAR
0.00
1
1.00
.25 0
0.75
1
0.75
24.28 2
24.28
.34 3
0.34
25.64 6
25.64
26
0.36
26.16
Forecast for month 9, (
t+1
).
5
25.80
Expected usage for current (month
8) period, (Smoothed D
t
).
0
0.25 α
2
24.71
Record for initial values when
month 9 actual figures become
available.
3
0.36
6
26.16

HP 12C Specifications

General

Type	Financial Calculator
Display	LCD, 10 digits
Manufacturer	Hewlett-Packard
Programming	Keystroke
Memory	20 memory registers
Functions	statistical functions
Dimensions	12.7 x 7.87 x 1.52 cm (5 x 3.1 x 0.6 in)