Here, unit of time is year. n = 10; So t = 1, 2, 3, ……….., 10; y = sales.
The given time series is written as shown in the following table:
| Time t |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
| SAles (in 0000) y |
200 |
216 |
228 |
235 |
230 |
232 |
236 |
235 |
230 |
233 |
Taking t on X-axis and y on Y-axis, points (1, 200), (2, 216), …, (10, 233) are plotted on the graph paper. Joining these points serially by lines,
the curve of the given time series is obtained as follows:
The curve passing through close to most of the points of the curve of original series is the parabolic curve showing the trend of given time series.
