218. A-N-N
Simple exponential smoothing
Example:
Given
- Smoothing parameter:
- Initial level:
- Data:
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | |
| 12 | 10 | 8 | 11 | 14 | 12 | 9 | 13 | 16 | 14 | 11 | 15 | 18 | 16 | 13 | 17 |
Step 1 — formula
Observation:
Innovation (rearrange):
State update:
One-step-ahead forecast:
Step 2 — apply at
Use and :
Step 3 — iterate
Values rounded to 4 decimal places; arithmetic performed at full precision.
| 1 | 12 | |||
| 2 | 10 | |||
| 3 | 8 | |||
| 4 | 11 | |||
| 5 | 14 | |||
| 6 | 12 | |||
| 7 | 9 | |||
| 8 | 13 | |||
| 9 | 16 | |||
| 10 | 14 | |||
| 11 | 11 | |||
| 12 | 15 | |||
| 13 | 18 | |||
| 14 | 16 | |||
| 15 | 13 | |||
| 16 | 17 |
Forecast for any future : (flat — SES has no trend).