New Delhi, Sept. 3 -- India's latest gross domestic product (GDP) figures have drawn widespread scrutiny since the data was released on Monday. Official statistics said April-June growth was 7.8%, which was hailed as a "Herculean feat" by Prime Minister Narendra Modi, but former finance secretary Subhash Garg claimed it was only 2.6%.

In reality, 7.8% is not the final figure and 2.6% isn't the correct one. Scepticism over the numbers stems from two factors: the overestimation of GDP under the revised series and high growth figures failing to translate into widespread prosperity.

Let's start with the official print. Quarterly estimates, released about two months after the end of a quarter, are often based on limited data. As more data be...