Q&A about the Consumer Price Index

A-1 What is CPI all about?

A-2 How is the CPI used?

A-3 How do you calculate the CPI?

A-4 Is there any international standard for calculating CPI?

A-5 When are results published?

A-6 What are the meaning of "Core index" and "Core-core index" as pertaining to the CPI?  (Updated on June 25, 2010)

A-7 Do you publish a seasonally-adjusted CPI?(Updated on October 31st, 2008)

A-8 What is imputed rent of an owner-occupied house?

A-9 How do you calculate the CPI for clothes and other commodities whose distribution and sales differ considerably from one season to another? (Added on March 26th, 2010)

B-1 Do you survey only a single specification for a single item? If so, that would not be able to faithfully reflect the actual changes in the prices of that item.

B-2 One new product after another shows up on the market. Does the CPI survey reflect prices changes of these new products?

C-1 Why is the CPI revised?

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

C-3 How do you select items used in calculation of the CPI? I suspect the CPI sometimes fails to reflect some new items in the market on a timely basis.

C-4 At the base revision of the CPI, how do you link old indices and new indices?

C-5 Following the base revision of 2005, the index and its rate of change over the year went down lower than those of the 2000 base. Why was this?

C-6 What effects does an index reset at the base revision have? (Added on December 28th, 2010)

D-1 What is quality adjustment with CPI for, and how do you make it? (Updated on October 31st, 2008)

D-2 What is the hedonic method?

E-1 How do you calculate the price indices of those items with which "the special calculation methods" are used? (Added on August 31st, 2007)

E-2 How do you calculate the price index for "Mobile telephone charges"?

E-3 How do you calculate the indices for "National expressway tolls" and "City expressway tolls"?

E-4 How do you calculate the CPI for school tuitions?

F-1 Is there anything I should note when I compare the CPI and Corporate Goods Price Index (CGPI) published by Bank of Japan?

F-2 I hear that the CPI and the GDP deflator (Published by the Cabinet Office) are different from each other. Why is this?

F-3 What are the differences between the average purchase prices recorded in the FIES and the CPI?

F-4 Some people say that the CPI might be higher than the actual consumer price level by 0.9 points or so. Is this true?