India measures prices and production through three headline indices: the Consumer Price Index for retail prices, the Wholesale Price Index for bulk trade prices, and the Index of Industrial Production for output. In February 2026 the CPI was rebuilt on a new base year of 2024, which makes this the single most interview relevant topic in official statistics this year.
The transcripts show boards working this ground hard. Real candidates were asked to name five or six indices, to explain the difference between IIP and WPI, to describe where CPI touches daily life, to list challenges in calculating CPI, and even to name the oldest CPI. Day 10 covers all of it, including what changed six months ago.
The new CPI series: what a board will expect you to know
The verified facts, from MoSPI’s own release. On 12 February 2026, the NSO released the new CPI series with base year 2024, replacing the 2012 base that had served for over a decade. The first reading under the new series put annual retail inflation for January 2026 at 2.75 percent.
Five changes worth carrying into the room. The item basket grew from 299 to 358 items, reflecting how consumption has changed, with services rising in weight. The weights now come from the Household Consumption Expenditure Survey 2023-24, replacing the 2011-12 consumption base. The classification moved to the international COICOP 2018 standard, reorganising the index from six broad groups into twelve divisions, which improves global comparability. House rent entered the rural index for the first time, where housing was earlier an urban only group. And price collection shifted to computer assisted personal interviewing on handheld devices, with the ministry signalling an intent to revise the base every three to five years rather than once a decade.
Why does CPI matter so much? Because the Reserve Bank’s inflation targeting framework, four percent with a two percent band, runs on it. That one connection, CPI to monetary policy, is the sentence that turns a definition into an answer.
CPI versus WPI: the classic comparison
A real board asked the IIP against WPI difference; the CPI against WPI version is just as common. The clean comparison: CPI measures price change at the consumer’s doorstep, including services, and is compiled by the NSO. WPI measures price change in bulk transactions between businesses, covers goods only, and comes from the Office of the Economic Adviser in the commerce ministry, still on its 2011-12 base. Inflation targeting uses CPI precisely because people live at retail, not wholesale.
And the oldest CPI question from the transcripts? The Labour Bureau’s Consumer Price Index for Industrial Workers is the veteran of the family, decades older than the general CPI, and still used for dearness allowance. Knowing that the Labour Bureau runs the worker specific CPIs while the NSO runs the general CPI is exactly the kind of precision boards enjoy.
IIP in three sentences
The Index of Industrial Production measures the volume of industrial output, month by month, across mining, manufacturing and electricity. It is a production index, not a price index, which is the heart of the IIP versus WPI question a real board asked. Its base remains 2011-12, with a revision to 2022-23 announced as part of the same modernisation drive that rebuilt the CPI and GDP, so expect the family of indices to keep moving to newer bases.
The challenge question
When a board asks what makes CPI calculation hard, they are inviting judgment, not complaint. Three honest challenges: keeping the basket representative as consumption changes, which is exactly why the base moved to 2024; collecting clean prices across thousands of markets, which the new series addresses with digital collection; and measuring housing and services, which resist simple pricing. Notice the shape: every challenge paired with what the system did about it. That is how a future officer talks about their own machinery.
A release today: the DAF Question Mapper, the second free resource of this series, is out. It walks every field of your form into the questions it will produce, with space to draft answers by hand. Everyone on the Interview 2026 list receives it automatically today.
Tomorrow, Day 11: the biggest number of all. How GDP is calculated, and the brand new 2022-23 series.
For both free resources, send the word INTERVIEW on WhatsApp to +91 842591 5355.
Frequently Asked Questions
What is the base year of the new CPI series?
2024. The new series was released by the NSO on 12 February 2026, with the item basket and weights drawn from HCES 2023-24. The first reading put January 2026 inflation at 2.75 percent.
What is the difference between CPI and WPI?
CPI measures retail prices paid by consumers, includes services, and is compiled by the NSO. WPI measures wholesale prices of goods only and is compiled by the Office of the Economic Adviser on a 2011-12 base.
What is the difference between IIP and WPI?
IIP measures the volume of industrial production, while WPI measures wholesale prices. One tracks output, the other tracks price.
Which is the oldest CPI in India?
The Consumer Price Index for Industrial Workers, compiled by the Labour Bureau, is the oldest of India’s consumer price indices and is used for dearness allowance.
Practice. Improve. Repeat.