New Delhi, Nov. 26 -- Former Reserve Bank of India (RBI) Governor Y.V. Reddy once quipped, "In India, not only the future, but even the past is uncertain."

Reddy was making an important point in his own witty way. RBI governors are not clairvoyant. They need data to make good policy decisions. Whether to raise or lower interest rates, or hold them steady, depends on the economy's macro fundamentals; in particular, whether GDP growth needs support or not, juxtaposed with RBI's primary responsibility to ensure price stability.

But data needs to be both timely and reasonably accurate-not subject to frequent or wide revisions, i.e.-if it is to serve any meaningful purpose.

For RBI governors, tasked with framing policy against a host of mac...