HP 12c Platinum Reference Guide

90 Forecasting
Forecasting:
RPN Mode:
1.
Key in the number 1 and press
\.
2.
Key in the selected α and press
?0-?1.
ALG Mode:
1.
Key in the number 1 and press
-.
2.
Key in the selected α and press
?0³?1.
3. From the selection routine or from a previous forecast:
Key in the smoothed average S
t-1
and press ?2.
Key in the trend T
t-1
and press ?3.
Key in the forecast
D
ˆ
t+1
and press ?6.
4.
Key in the current data value and press
t. The output is the error in forecasting the
value just entered.
5.
Press
t. The displayed value represents the forecast for the next period.
6.
Record the following values:
:0 (α), :2 (S
t-1
), :3 (T
t-1
) and :6 D
ˆ
(
t+1
) for
use as initial values in the next forecast. You may also wish to record
:5 (D
t
).
7. Repeat steps 4, 5, and 6 for the next forecast if available.
Example: Select the best smoothing constant based on sales (in thousands of dollars) of
22, 23, 23, 25, 23, 27, 25. Given the current sales in month 8 of 26, forecast the following
month.
Select the smoothing constant (α ):
12c platinum / 12C
RPN Keystrokes
12c platinum
ALG Keystrokes
Display Comments
fCLEARH fCLEARH
0.00
1\ 1-
1.00
.5?0- .5?0³
0.50
?1 ?1
0.50
22?2 22?2
22.00
23?6t 23?6t
0.00
t t
23.00
23tt 23tt
23.25
25tt 25tt
25.25
23tt 23tt
23.69
27tt 27tt
27.13
25tt 25tt
25.95
:4 :4
23.61
Cumulative error (∑e
2
).
:0 :0
0.50
Smoothing constant (α ).

HP 12c Platinum Specifications

General

Digits	10 digits
Battery type	CR2032
Type	Financial
Form factor	Pocket

Weight and Dimensions

Weight	110 g
Dimensions (WxDxH)	79 x 129 x 15 mm