4.6 Other change values
Monthly indices can be linked to create four or six-month periods, for example, which can then be compared with preceding periods of the same length. Another way to calculate 12-month change is to work with the monthly change rate and assume that the latest one-month change will continue at the same rate over the next 11 months.
For example, the one-month change in January 2003 was 0.12 per cent. Working with this figure, the annual change for 2003 would be 100.12 12 = 101.44 = 1.4 per cent.
We can also use monthly index values to compute the change in sliding averages. For example, the average of the index values for the three most recent months can be compared with the average of the indices for the preceding three months.
CPI 2000=100 index values for 2000-2003
| Month | 2001 | 2002 | 2003 |
| January | 100.89 | 103.19 | 104.59 |
| February | 101.51 | 103.35 | 105.28 |
| March | 102.06 | 103.90 | 105.57 |
| April | 102.53 | 104.33 | 105.44 |
| May | 103.21 | 104.56 | 105.31 |
| June | 103.20 | 104.34 | 105.19 |
| July | 102.43 | 104.15 | 104.64 |
| August | 102.75 | 104.15 | 104.78 |
| September | 103.49 | 104.53 | 105.21 |
| October | 103.26 | 104.80 | 105.10 |
| November | 102.80 | 104.47 | 105.00 |
| December | 102.76 | 104.46 | 105.09 |
| Average | 102.57 | 104.18 | 105.10 |
1. October-December 2002 vs. January-March 2003
2. November 2002-January 2003 vs. February-April 2003
The sliding average of these periods is:
In other words the change in the three-month sliding average is 0.3 per cent.
| 4.1 | 4.2 | 4.3 | 4.4 | 4.5 | 4.6 | 4.7 | 4.8 | 4.9 | 4.10 |
- Module:
Indices - Lesson:
Using indices to perform calculations and to express change - Topic:
Other change values
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