Double deflation is theoretically superior to single deflation in GDP estimation but is criticized as data-intensive for India. Discuss the methodology and the debate surrounding its recent adoption in India's GDP series.

Real Gross Value Added (GVA) must measure volume, not price. Double deflation achieves this by deflating an industry's gross output and its intermediate inputs with separate price indices. India's new GDP series with base year 2022-23, released by MoSPI on 27 February 2026, adopts it for the first time [1] — and has triggered a sharp methodological debate.

The methodology

• Real GVA = deflated gross output − deflated intermediate consumption, each using its own deflator; this is the System of National Accounts benchmark [2].
• Single deflation (old 2011-12 series) applied one index — typically WPI — to both sides, implicitly assuming input and output prices move together [2].
• That assumption collapses during commodity or import price shocks, distorting manufacturing GVA in either direction.
• MoSPI states single deflation has been "completely done away with", with deflators applied at a more granular, item level [1].

The case for adoption

• Restores comparability with international practice, where double deflation is standard [2].
• Responds to external scrutiny: the IMF's 2025 Article IV Consultation flagged the value of further data-quality enhancement [3].
• Applied in the rebased series, real GDP grew 7.2% (2023-24) and 7.1% (2024-25) [1], with 7.6% estimated for 2025-26 [4].

The criticism

• India lacks a comprehensive Producer Price Index; WPI omits services and maps poorly onto actual input baskets — making the method data-intensive beyond current capacity.
• Former Chief Statistician Pronab Sen and former Finance Secretary S.C. Garg question deflator credibility, citing large revisions in provisional estimates.
• No back series on the new method has been released, blocking historical comparison.
• NITI Aayog Vice-Chairman Ashok Kumar Lahiri counters that separating inputs from outputs is neither impossible nor difficult.

Double deflation is a genuine methodological advance; the dispute is about statistical infrastructure, not theory. Expediting a full PPI, publishing a back series, and strengthening the National Statistical Commission would convert a contested reform into a credible one — anchoring economic governance in trustworthy data.