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Q&A about the Consumer Price Index

[A. About the consumer price index (CPI)]

A-1 What is CPI all about?

A-2 Since when has the CPI been calculated?

A-3 What is the the index reference period? And what is the weight reference period?

A-4 How is the CPI used?

A-5 What are the meaning of "Core index" and "Core-core index"?

[B. Calculation of the CPI]

B-1 How do you calculate the CPI?

B-2 Is the CPI calculation method of Japan as same as that of major countries?

B-3 How do you select items used in calculation of the CPI?

B-4 How do you calculate the CPI for clothes and other commodities whose distribution and sales differ considerably from one season to another?

You seem to survey the prices of summer and winter clothes when they comes on the market seasonally. Yet how do you calculate the CPIs for those months not directly covered by the survey?

B-5 What is imputed rent of an owner-occupied house?

[C.Uses of the results]

C-1 When are results published?

C-2 Do you publish a seasonally-adjusted CPI?

C-3 Where are the result of Quarterly and Half-yearly average indices are published?

[D. Revisions to the bases]

D-1 Why is the CPI revised?

D-2 Isn't the CPI's base revision interval of five years too long to cope with rapid changes in the consumption pattern?

D-3 At the base revision of the CPI, how do you link old indices and new indices?

D-4 Why does the revised 2010-base show a decrease in change from the same month of the previous year, compared with the 2005-base CPI?

D-5 What impact does an index reset due to a base revision have?

D-6 How much impact did the index reset due to the 2010-base revision have?

[E. Midpoint-year review]

E-1 What is a midpoint-year review?

[F. Quality adjustment]

F-1 What is quality adjustment with CPI for, and how do you make it?

F-2 What is the hedonic method?

F-3 I heard that, with the hedonic method, the price of an item is considered to be gone half off if its performance has doubled. Is this true?

[G. Frequently asked questions about the CPI]

G-1 One new product after another shows up on the market. Does the CPI survey reflect prices changes of these new products?

G-2 Are private brand commodities surveyed?

G-3 Are disucount stores included as survey subjects?

G-4 Will the CPI appropriately reflect the change of quality such as functional improvement of products?

G-5 It is said that there is an upward bias in Japan's CPI. Is this true?

G-6 I heard that Japan has adopted a different method for selecting products subject to the RPS from that of the United States.

Is Japan's selection method different from other countries?

G-7 Is there anything I should note when I compare the CPI and Corporate Goods Price Index (CGPI) published by Bank of Japan?

G-8 I hear that the CPI and the GDP deflator (Published by the Cabinet Office) are different from each other. Why is this?

[H. Consumer Price Index calculated by Laspeyres' chain index method]

H-1 What kind of index is "Consumer Price Index calculated by Laspeyres' chain index method " compiled as one of the supplementary indices?

H-2 How is the chain index calculated?

H-3 What is the difference in the rate of change between the chain index and the fixed base Laspeyres index?

H-4 Why didn't you position the chain index as official?

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