Explanation of Bank of Japan Overseas Commodity Index (OCI)
January 7, 2013
Bank of Japan
Research and Statistics Department
Compilation section : Economic Research Division, Research and Statistics Department
Frequency of compilation : Monthly basis
Time of release : Basically on the first business day of the following month. See 4 below.
Method of release : Bank of Japan Internet web site
Publications : Financial and Economic Statistics Monthly
Commencement of data : January 1990
1. Purpose and Functions
The Bank of Japan Overseas Commodity Index (OCI) shows general movements of major overseas commodity prices. This index is considered to be one of the leading indicators of Japan's import prices. It is also useful in the sense that developments in the world economy are reflected in prices of commodity markets.
2. Release Series
End of month figures, denominated in U.S. dollar (CY 2010 average = 100).
The 2010 base OCI is a weighted average (geometric mean) of prices (U.S. dollar base) of nineteen selected goods in overseas commodity markets. The weights are calculated using Japanese Import Value in the Trade Statistics of Japan in 2010. The selected commodities and their corresponding weights are as follows:
The base year and weights are to be revised every five years, following the revision of the CGPI (Corporate Goods Price Index).
Note that in connecting indices of different base years, the link coefficient is used as in the case of regular price indices (CGPI, etc). For example, a 2010 base linked index for the period January 2005 - December 2009 is calculated as follows:
4. Release Date
As a general rule, the index is released on the first business day of the following month. The release date may be occasionally postponed for two or three business days, when there are successive holidays from the end of a month to the beginning of the following month (for example, in January or May). This is because in such cases source data may not be available in time. Also, when source data are not readily obtained for some reason, provisional figures reflecting only available information at the time may be released. In such an event, revised figures are released in the following month.