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The calculation of the Consumer Price Index (CPI) started in August 1946 in Japan. After several revisions, the Statistics Bureau, the Ministry of Internal Affairs and Communications revised the base period and the weight reference period to the calendar year 2015 in August 2016, which is the fifteenth revision.

This manual explains the method of index calculation and main points of the 2015-base revision of the CPI in detail.

November 2016

Statistics Bureau, Ministry of Internal Affairs and Communications

I Outline of the 2015-Base Consumer Price Index (PDF:100KB)

1 Characteristics of the index

2 Outline of the index

3 Index groupings

4 Publication of the CPI

[Reference] Treatment of the housing services of owner-occupied houses

II Outline of the 2015-Base Revision of the Consumer Price Index (PDF:128KB)

1 Purpose of revision and statistical standard

2 Revision of the index reference period

3 Revision of weights

4 Revision of items

5 Revision of model formulas

6 Increases and refinement of published groupings

7 Basic policy of index calculation

(Appendix 1) Index items revised in 2015 base

(Appendix 2) Major items subject to name change in 2015 base

III Calculation of the Consumer Price Index

Chapter 1 Calculation of the prices in the comparison period (Pt) (PDF:126KB)

1 Calculation of the prices in the comparison period

2 Substitution of the prices in the comparison period

Chapter 2 Quality adjustment during calculation of the prices in the comparison period (PDF:289KB)

1 Necessity of quality adjustment for calculating prices in the comparison period

2 Method of quality adjustment

Chapter 3 Calculation of the prices in the base period (P0) (PDF:110KB)

Chapter 4 Calculation of the weight (W0) (PDF:205KB)

1 Scope of the Family Income and Expenditure Survey (FIES) items adopted for the weights

2 Calculation of the weights for the basic classification indices

3 Calculation of the weights for the goods and services classification

4 Calculation of the weights for index based on baskets of specific household groups

Chapter 5 Method of index calculation and the index grouping (PDF:245KB)

- Updated in line with adding new analytical indices(March 2017)

Method of index calculation and the index grouping (PDF:100KB)

1 Index formula

2 Process of the index calculation

3 Processing of items for which prices in the comparison period are missing

4 Calculation of average indices for calendar year, fiscal year and so on

5 Calculation of the rate of change

6 Calculation of the contribution to the total change

7 Index grouping

Chapter 6 Linking of old and new indices (PDF:84KB)

1 Method of linking old and new indices

2 Range of linked indices

3 Notes on the use of linked indices

Chapter 7 Seasonal adjustment (PDF:137KB)

- Updated in line with adding new analytical indices(March 2017) Seasonal adjustment (PDF:65KB)

1 Seasonal variation and seasonal adjustment

2 Calculation of seasonally adjusted indices

3 Data used to calculate seasonally adjusted indices

4 Recalculation of seasonally adjusted indices

5 Available grouping of seasonally adjusted indices

[Reference] Method of seasonal adjustment

Appendix 1 Calculation of the price indices for PCs and cameras by hedonic approach (PDF:149KB)

Appendix 2 Calculation of model items

List of subject items (74 items) (PDF:65KB)

Calculation of model items (in Japanese only) (PDF:870KB)

Appendix 3 Calculation of the weights for the imputed rent (PDF:53KB)

Appendix 4 Calculation of the CPI by Laspeyres' Chain Index method (PDF:117KB)

Appendix 5 Details of seasonal adjustment with X-12-ARIMA (PDF:48KB)

- Updated (The ARIMA models are applied from the release of Japan December 2016 results, Ku-area of Tokyo January 2017(preliminary) results)Details of seasonal adjustment with X-12-ARIMA (PDF:72KB)
- Updated in line with adding new analytical indices (The ARIMA models are applied from the release of Japan January 2017 results, Ku-area of Tokyo February 2017(preliminary) results)Details of seasonal adjustment with X-12-ARIMA (PDF:66KB)

IV Related documents for the 2015-Base Consumer Price Index (in Japanese only except for 1)

1 List of information for items of the 2015-Base CPI (PDF:129KB) (Excel:328KB)

- Updated in line with adding new analytical indices(March 2017)

List of information for items of the 2015-Base CPI (PDF:75KB) (Excel:327KB)

2 List of municipalities for the price survey (PDF:435KB) (Excel:60KB)

3 Aggregation table from the items to the groups (basic classification) (PDF:192KB)

4 Aggregation table from the items to the groups (goods and services group) (PDF:433KB)

5 Division and integration of the FIES items to the CPI items (PDF:669KB)

6 Table of correspondence of groups and items in 2015-base and 2010-base (PDF:486KB)

V Weights of the 2015-Base Consumer Price Index (in Japanese only)

1 The number of items and weights by subgroups (Japan / the Ku-area of Tokyo, the actual number / per ten thousand)

(PDF:431KB) (Excel:50KB)

- Updated in line with adding new analytical indices(March 2017)

(PDF:21KB) (Excel:50KB)

2 The number of items and weights by goods and services (Japan / the Ku-area of Tokyo, the actual number / per ten thousand)

(PDF:413KB) (Excel:41KB)

3 Weights by subgroups (City groups / District / Major Metropolitan Areas / Cities with Prefectural Governments, the actual number / per ten thousand)

(PDF:722KB) (Excel:123KB)

- Updated in line with adding new analytical indices(March 2017)

(PDF:104KB) (Excel:124KB)

4 Monthly weights of fresh food (Japan / the Ku-area of Tokyo, the actual number / per ten thousand)

(PDF:592KB) (Excel:70KB)

5 Weights by specific household groups (Japan, the actual number / per ten thousand)

(PDF:477KB) (Excel:79KB)

- Updated in line with adding new analytical indices(July 2017)

(PDF:34KB) (Excel:85KB)

6 Weights by goods groups classified according to elasticity to living expenditure (Japan, the actual number / per ten thousand)

(PDF:633KB) (Excel:146KB)

7 Weights by annual purchase frequency classes (Japan, the actual number / per ten thousand)

(PDF:672KB) (Excel:164KB)

VI History of the CPI in Japan (PDF:17KB)

VII Outline of the Retail Price Survey (Trend Survey) (PDF:73KB)

1 Purpose

2 Survey system and survey areas

3 Survey items and specifications

4 Survey date

5 Survey methods

6 Number of collected prices

VIII Reference materials (in Japanese only) (PDF:443KB)

1 Resolution concerning consumer price indices, adopted by the 17th International Conference of Labour Statisticians (2003) -excerpt-

2 Application examples of the Consumer Price Index

3 Japanese statistical standard on the base period of index

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