Survey vs satellite: the new ways India is being measured

India’s classic statistical instruments — the census, the big household surveys — are slow, careful and increasingly stale. In the gaps, a new generation of measurements has grown up: toll-booth pings, tax invoices, electricity meters, satellite photos of the country at night.

The trade is speed against representativeness. A survey painstakingly includes the household with no vehicle, no GST number and no electricity connection; the new instruments see only the connected. Night-lights data famously suggested growth in places the surveys showed distress — and both were measuring truthfully, just measuring different Indias.

Administrative data tells you what the formal economy did yesterday. Surveys tell you what the whole country did two years ago. India needs both eyes open.

The craft for readers is provenance: before trusting a chart, ask what instrument produced it, whom that instrument can see, and who is standing outside its frame.