43.9%. That is how fast iron ore output supposedly grew in June - a single sector's swing large enough, on its own, to push India's entire core industrial growth rate to a five-month high.

A 5% Growth Number That Is Also a Measurement Choice Start with the headline: core industries grew 5% in June, the fastest in five months.

Now zoom into what actually drove it - iron ore, a single sector newly added to the index, grew 43.9%. That one number, on a sector carrying just a 4.9% weight, was enough to lift the whole index's growth rate meaningfully above where it would otherwise have landed.

The story here isn't really "industry is accelerating." It's that changing how you measure something changes what the measurement tells you - and this month's headline number is inseparable from the methodology that produced it.

The Mechanism: What Actually Changed

Three things moved together in this release. First, the base year shifted from 2011-12 to 2022-23 - meaning growth is now measured against a more recent, more representative snapshot of the economy's structure. Second, iron ore was added as a ninth core sector, recognising its weight in today's industrial supply chains in a way the 2011-12 basket never captured.

Third, the underlying data itself changed shape: steel is now measured on gross production instead of net and coal counts only "raw coal," dropping washed coal and middlings that were previously double-counted. Each of these is defensible on its own terms - a base year over a decade old genuinely does misrepresent a changed economy.

But together, they mean this month's 5% is not comparable, in any simple sense, to last year's core-sector growth figures under the old series. The Ministry's own revision shows this starkly: FY25 growth was revised down sharply, from 6.9% to 4.3%, purely by changing the ruler, not the underlying activity.

Why the Base Effect Matters More Than the Headline

Iron ore's 43.9% jump gets its power almost entirely from a base effect - the sector had contracted 16.4% in June last year, so even a modest recovery looks dramatic against that low starting point. This is the oldest trap in reading growth statistics: a low base flatters this month's number regardless of whether underlying capacity or demand actually improved.

Strip out iron ore's outsized swing and the more durable signal is that electricity and cement grew a steady 9.8% each on genuine demand - heat and a weak monsoon driving power use - while the entire hydrocarbon cluster (crude oil, natural gas, refinery products, fertilisers) contracted.

The Aggregate Picture, Read Correctly

Zoom back out: the headline 5% is real, verified and not manipulated - but it is also the product of a basket, a base year and an accounting convention, all of which just changed simultaneously. For an aspirant, the exam-relevant skill this story teaches isn't memorising the new weights.

It's recognising that whenever a government revises an index's base year and composition in the same release as a strong headline number, the two facts need to be read together, not the second one alone.