Inflation measurement is the process of tracking the change in the price levels of a basket of goods and services over a specific period. In India, inflation is primarily measured using two sets of indices: the Wholesale Price Index (WPI) and the Consumer Price Index (CPI). Since 2014, based on the Urjit Patel Committee recommendations, the Reserve Bank of India (RBI) has adopted CPI (Combined) as the primary anchor for its monetary policy.
Consumer Price Index (CPI)
CPI measures the change in the price level of a basket of consumer goods and services purchased by households. It reflects the cost of living and the impact of inflation on the end consumer.
Key Variants of CPI in India
- CPI (Rural, Urban, Combined): Compiled by the National Statistical Office (NSO) under the Ministry of Statistics and Programme Implementation (MoSPI). The base year is 2012.
- CPI for Industrial Workers (CPI-IW): Compiled by the Labour Bureau (Ministry of Labour and Employment). It is used for fixing the Dearness Allowance (DA) of government employees and wage revisions in the organized sector. The base year was recently updated to 2016.
- CPI for Agricultural Labourers (CPI-AL): Compiled by the Labour Bureau for fixing minimum wages for agricultural sectors. Base year: 1986-87.
- CPI for Rural Labourers (CPI-RL): Compiled by the Labour Bureau for rural casual labor. Base year: 1986-87.
Weightage in CPI (Combined)
| Category | Approximate Weight (%) |
| Food and Beverages | 45.86% |
| Housing | 10.07% |
| Fuel and Light | 6.84% |
| Clothing and Footwear | 6.53% |
| Pan, Tobacco, and Intoxicants | 2.38% |
| Miscellaneous (Services, Health, Education) | 28.32% |
Wholesale Price Index (WPI)
WPI measures the change in the price of goods sold and traded in bulk by wholesale entities to other businesses. It does not include the service sector. It is compiled by the Office of the Economic Adviser, Department for Promotion of Industry and Internal Trade (DPIIT), Ministry of Commerce and Industry.
Weightage and Composition of WPI
The current base year for WPI is 2011-12. It tracks a total of 697 items.
- Manufactured Products: Holds the highest weightage at 64.2%.
- Primary Articles: Includes food and non-food articles, weighing 22.6%.
- Fuel and Power: Weighs 13.2%.
Comparative Analysis: CPI vs. WPI
| Feature | Consumer Price Index (CPI) | Wholesale Price Index (WPI) |
| Primary Focus | Retail prices paid by consumers. | Wholesale prices at the factory gate. |
| Commodities | Goods and Services. | Only Goods. |
| Compiling Agency | NSO (MoSPI) & Labour Bureau. | Office of Economic Adviser (Min. of Commerce). |
| Base Year | 2012 (Combined). | 2011-12. |
| Food Weightage | Very High (~46%). | Relatively Low (~24% including food components). |
| Policy Use | Anchors RBI’s Inflation Targeting. | Used for GDP deflator and industrial tracking. |
The GDP Deflator
The GDP Deflator is a comprehensive measure of inflation that tracks price changes of all goods and services produced domestically. Unlike CPI or WPI, it is not based on a fixed basket of goods but changes automatically with consumption and investment patterns.
- Formula: GDP Deflator = Nominal GDP/Real GDP × 100.
- Significance: It covers the entire economy, including government services and capital goods, which are often missed by CPI and WPI. However, it is only available quarterly or annually, making it less useful for real-time policy adjustments.
Important Indices and Concepts for UPSC Prelims
- Producer Price Index (PPI): A proposed index (recommended by the B.N. Goldar Committee) that measures the average change over time in the selling prices received by domestic producers. Unlike WPI, it excludes indirect taxes and trade margins, providing a clearer picture of production costs.
- Service Price Index: While CPI includes services, a dedicated Service Price Index is under development in India to track the business-to-business (B2B) service inflation more accurately.
- Housing Price Index (HPI) / RESIDEX: Compiled by the National Housing Bank (NHB), it tracks the movement in prices of residential properties across major Indian cities.
- Food Inflation: Tracked specifically through the Consumer Food Price Index (CFPI), which is a sub-component of the CPI but focuses exclusively on the food basket.
Technical Trivia and Facts
- Base Year Revision: Base years are updated periodically to capture changes in consumption patterns. The government is currently in the process of evaluating a move to 2017-18 or later for WPI and CPI.
- Laspeyres Formula: Both CPI and WPI in India generally use the Laspeyres price index formula, which uses base-period quantities to weight the prices.
- Headline vs. Core in Measurement: While the NSO releases “Headline” figures (all items), “Core” inflation is derived by stripping out the volatile ‘Food and Beverages’ and ‘Fuel and Light’ groups from the CPI.
- Base Effect: This refers to the impact of the corresponding period’s inflation in the previous year on the current inflation rate. If the price index was unusually low in the previous year, even a small rise in prices today will show a high inflation percentage.