4.4 12-month change and average annual change
To measure 12-month change, the index value for a given month is compared with the value for the corresponding month in the previous year.
For example, the 12-month change in the consumer price index in 2002 is calculated as follows:
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 | |
| Average | 102.57 | 104.18 |
The 12-month change in the consumer price index in December 2002 is 1.7 per cent.
To calculate the average annual change, the arithmetic mean of the index values for all months in the year are compared with the arithmetic mean of the values for all months in the previous year.
For example, the annual change in the consumer price index in 2002 is calculated as follows:
The arithmetic mean of the index values for the 12 months in 2002:
(103.19+103.35+103.90+104.33+104.56+104.34+104.15+104.15+104.53+104.80+104.47+104.46) /12 = 104.18
The arithmetic mean of the index values for the 12 months in 2001:
(100.89+101.51+102.060102.53+103.21+103.20+102.43+102.75+103.49+103.26+102.80+102.76) /12 = 102.57
The annual change in the consumer price index in 2002 is 1.6 per cent.
| 4.1 | 4.2 | 4.3 | 4.4 | 4.5 | 4.6 | 4.7 | 4.8 | 4.9 | 4.10 |
Telephone +358 9 17 341