|
Motivation: Our national source for Chile reports the headline consumer price index (CPI) with a base year of 2009 and in not seasonally adjusted (NSA) terms, beginning in January 2009.
Response: We have extended the history on the NSA fundamental series to March 1928 using the predecessor base-2008 index. Additionally, for international consistency, we have created a seasonally adjusted (SA) counterpart.
Properties: Both series begin in March 1928. The index base is 2009=100. Expect the SA supplement to be revised with each new historical value appended to the fundamental.
Method:
- Input: CPITTUM.ICHL, reported fundamental (2009=100), starts Jan. 2009.
- Input: CPITT08UM.ICHL, predecessor (Dec. 2008=100), starts Mar. 1928.
- Output: CPITTUM.ICHL, extended by 80 years to Mar. 1928.
- Output: CPITTAM.ICHL, supplement (2009=100, SA), starts Mar. 1928.
- Extend the NSA series backwards to March 1928 using the growth rates of the previously reported base-2008 index series.
- Seasonally adjust using the U.S. Census Bureau's X-12 ARIMA program.
|