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Consumer Price Index - Calculating Index Changes

 
Movements of the indexes from one period to another are usually expressed as percent changes rather than changes in index points because index point changes are affected by the level of the index in relation to its base period while percent changes are not. This example illustrates the computation of index points and percent changes.
 
Step 1:
Calculating the index point change:
CPI- Anchorage 2013
Less CPI for previous period- Anchorage 2011
212.381
-205.916
Equals index point change 6.465

Step 2:
Calculating the percent change:
Index point difference Divided by the previous index (Anchorage 2012) 6.465 / 205.916
= 0.031396
Results multiplied by 100
Percent change (Anchorage CPI 2013)
0.031396 * 100 = 3.13963
3.1 (rounded 3.13963)