|
Motivation: Our national source for China reports consumer price trends as month-over-month and year-over-year growth rates, which are inconvenient for long-term analysis.
Response: For international consistency, we have computed an index with a single base year, and a seasonally adjusted version of same (series CPITTUM.ICHN and CPITTAM.ICHN, respectively).
Properties: Both series begin in January 1986 and have a base of 2005=100. Expect the NSA series to remain in sync with the reported values, and for the SA series to be revised with each new historical value appended to the NSA series.
Method:
- Input: CP%TTUM.ICHN, Reported Y/Y percent change, starts January 1987.
- Input: CP%TTMUM.ICHN, Reported M/M percent change, starts January 2005.
- Create index CPITTUM.ICHN using the M/M growth rates of CP%TTMUM.ICHN from January 2005 to December 2005. (We use only part of this series because the Y/Y has official primacy.)
- Grow the index forward and backward using the reported Y/Y percent change, CP%TTUM.ICHN.
- Rebase the index to 2005=100 by dividing the entire series by the average of its 12 values in 2005.
- Seasonally adjust using the U.S. Census Bureau's X-12 ARIMA program, producing CPITTAM.ICHN.
|