India, June 5 -- Last week's release of early results from the sixth National Family Health Survey (NFHS) made headlines, not just for its main findings, but also for information that the NFHS no longer reports. The NFHS factsheet carried 101 indicators where the previous round had 131. Gone was the prevalence of anaemia - the condition that affects roughly two-thirds of India's children and more than half its pregnant women, by the last count - as well as infant and child mortality rates, the sex ratio at birth, and the share of households cooking with clean fuel.

Some of these changes were defensible. Anaemia in past rounds was measured by pricking a finger and reading a drop of capillary blood, a method that is convenient in field sur...