"Revising base years of macroeconomic indicators is essential but not sufficient for credible statistics." Discuss with reference to the new IIP series (2022-23).

Credible statistics must be current, comprehensive, comparable and timely. MoSPI's new Index of Industrial Production (IIP) series moves the base year from 2011-12 to 2022-23 [1], in step with the revisions of GDP and CPI [2]. This makes the index current. Its credibility, however, also depends on how the index is designed and how data are collected.

Why base revision is essential

• Updated structure: Weights now come from GVA and ASI data for 2022-23. Manufacturing has a weight of 76.062, mining's weight falls from 14.372 to 11.053, and the basket grows from 407 to 463 item groups [1].
• Wider coverage: Gas supply and water supply, sewerage and waste management have been added [1].
• Better deflator: For value-based items, Output PPI replaces WPI. This covers 234 items and 36.02% of the weight [3].
• Fixing an ageing panel: By the end of the old series, factories that had closed still carried about 8.9% of the weight. This made growth look lower than it was [4].
• Comparability: Common base years let GDP, CPI and IIP be compared with each other [2].

Why it is not sufficient

• Organised-sector bias: Small unincorporated units are largely left out. The TAC calls an ASUSE-based index only "forward-looking" [4].
• Fixed-base rigidity: Under the Laspeyres method, weights stay frozen for about a decade. Big new plants, such as those in PLI sectors, can be added only "on rarest of rare occasions". The USA, UK and EU instead chain-link their indices, updating weights about every year [4].
• Imputation risk: The September 2026 Quick Estimate had a weighted response rate of 86.5%, against 92.0% for the final August figure [5]. Data for missing factories are filled in from the growth of factories that did report [4].
• Revision communication: The WPI-based series released on 1 June 2026 was replaced by a PPI-based one within weeks [3].
• Pending tools: There is no seasonally adjusted IIP yet, and no GST-based business register. State IIPs follow different methods, and old and new series are linked only for the headline index and broad sectors [4].

A new base year shows when the economy is measured; credibility depends on how it is measured. MoSPI should carry out the TAC roadmap: a chain-linked index alongside the fixed-base one, a GST business register, seasonally adjusted data, an index for unincorporated units and common methods for states [4]. With clear revision calendars, these steps would bring India in line with the UN's IRIIP 2010 guidance [4]. Policymakers would then have reliable, evidence-based statistics.