Periodic revision of base years of economic indicators is essential for credible policymaking. Comment in the context of the 2022-23 base revision of WPI, IIP and GDP.

The base year is the reference period that sets an indicator's basket and weights. In 2026, India moved WPI, IIP and GDP together from 2011-12 to 2022-23 [2][3][4]. The move makes policymaking more credible, as long as the transition risks are managed.

How the 2022-23 revision strengthens policymaking

• Updated basket: WPI items rose from 697 to 957. Solar, wind and nuclear electricity were added [2], so the index now reflects the shift to renewables.
• Current weights: Manufactured Products now carry 63.13% of the weight and the WPI Food Index 24.99% [1]. This gives RBI and the Finance Ministry a truer picture of price pressure.
• Better deflators: The release added the Output PPI, a trial Input PPI and a Service PPI [2]. MoSPI now uses Output PPI instead of WPI to deflate IIP item groups recorded in value terms. This version replaced the WPI-based series released on 1 June 2026 [3], which gives a more accurate measure of real output.
• Consistent GDP: The new GDP series uses 2022-23, a normal year after COVID, as its base. It uses double deflation and new data such as GST records [4]. With all three indicators on the same base year, the price, output and growth figures are consistent with each other.
• Global alignment: The IMF's PPI Manual notes that most countries have replaced WPI with a PPI aligned to the System of National Accounts (SNA) [5]. India's shift makes its figures easier to compare internationally.

Concerns that need managing

• Breaks in comparability: The back series starts only in April 2023 [2]. Comparisons with old-series figures are not like-for-like, and revised growth figures make long-run trends harder to read.
• Provisional reliability: The September 2026 provisional WPI was based on an 83.4% weighted response rate, against 98.97% for the final July figure [1]. Provisional figures can therefore be revised.
• Unfinished shift: The Input PPI covers manufacturing only and is still a trial. The Service PPI covers just seven services, and WPI will run alongside PPI for five years [2].
• Long gap: The 2011-12 base stayed in use for over a decade, so policy relied on outdated weights for years.

Overall, the 2022-23 revision updates baskets and weights and introduces better deflators, which makes India's statistics more credible. India should next adopt a fixed revision calendar, publish full back series, and extend the PPIs to the whole economy. This would deliver the quality, timely data called for under SDG 17.18 and support evidence-based governance.