Home / Opinion / Columns /  The professor who taught the world the art of sampling

In the summer of 1946, at the ‘nuclear’ session of the United Nations Statistical Commission (UNSC), a representative of a British colony made an impassioned plea for laying down globally accepted standards for conducting large-scale sample surveys. Prasanta Chandra Mahalanobis argued that household surveys would become invaluable data sources for many developing countries that were not fortunate enough to have the kind of rich administrative datasets that advanced economies boasted of.

Mahalanobis’s suggestion was accepted, and given his unique experience in conducting such surveys at the Indian Statistical Institute (ISI), he was asked to chair the first sub-committee of the UNSC on sampling. The global manual on sampling, which the world would follow for the next few decades, owed a large debt to Mahalanobis and his colleagues’ work at the ISI. ISI’s innovations—such as using a pilot survey to test a survey and the use of replicating samples to ascertain the magnitude of different kinds of errors in surveying—were adopted across the world.

Mahalanobis’s contributions to the global statistical body went beyond standardizing sampling norms. When the UNSC set up a committee to prepare a manual for computing national accounts (through which a country’s gross domestic product or GDP is calculated), Mahalanobis’s protege and a national income expert, Moni Mohan Mukherjee was asked to join the taskforce. Mahalanobis also chaired the 8th and 9th sessions of the UNSC in the 1950s, and attended all its sessions till his death. When he passed away in 1972, the UNSC’s condolence note said that it had lost its “doyen".

Mahalanobis’s interventions on the global stage were not designed to appropriate the tag of ‘Vishwaguru’ for himself or for his institute. It was motivated by a desire to fill the yawning data gaps that India and much of the developing world faced, without blindly copying the statistical norms and practices followed in the West. Ronald Fisher—arguably the greatest statistician of the 20th century—once said that what impressed him most about Mahalanobis’s work was that it was not “imitative".

Like most intellectuals of that era, Mahalanobis had profound faith in planning as an instrument of growth and development. Good plans needed good data, and that motivated him to set up a number of data-gathering institutions in the first few years after India’s independence. The national income unit of the finance ministry, headed by Mukherjee, was hived off into a separate department called the Central Statistical Organization. To scale up the ISI’s early surveys and fill data holes in computing national income, the National Sample Survey (NSS) system was established. The Annual Survey of Industries (ASI) was set up to collect regular data on industrial activity.

Mahalanobis’s ideas on planning have not aged well. But his statistical interventions have stood the test of time. The manner in which India and much of the world collect data is shaped by his foundational ideas. Where Mahalanobis (and India) led, the rest of the world followed, wrote the Nobel-winning economist Angus Deaton in a 2005 article.

Mahalanobis had a few things going for him. Born in a prominent Bengali Brahmo family, his social network was an important asset. He was close to Rabindranath Tagore, at whose house he would first get to spend long hours with Jawaharlal Nehru. As chairman of the Congress’s Planning Committee, Nehru was worried about data gaps much before India won independence, and sought Mahalanobis’s counsel on ways to fill such gaps.

The unstinting support of Chintaman Dwarkanath Deshmukh was another important factor. As a civil servant and central banker, Deshmukh helped Mahalanobis access government funds to tide over the recurrent financial crises that the ISI faced in its early years. Later, as finance minister of independent India, it was Deshmukh who helped fund Mahalanobis’s ambitious survey plans. Deshmukh tutored the professor on ways to deal with the labyrinthine British bureaucracy and later its Indianized version, Mahalanobis’s biographer Ashok Rudra wrote.

Despite these advantages, it was never an easy ride for Mahalanobis. Rudra documented a life-long struggle to stabilize the ISI’s finances. As late as 1954, Mahalanobis felt frustrated enough to consider resigning as its director. “My struggles have been mostly against a machine which is impersonal, and incapable of responding to changing needs," Mahalanobis wrote in a letter to Deshmukh (then the finance minister as well as ISI president) explaining how red-tapism was throttling the institute’s work.

In his recent book Planning Democracy, historian Nikhil Menon documents Mahalanobis’s struggle to obtain computers to handle the ‘big data’ of his era. Mahalanobis realized that without computers, NSS data could never be tabulated on time. He moved heaven and earth to get them. The first digital computer in the country was installed at the ISI in 1956 to process NSS data. Soon it was processing data for other institutions too.

As we celebrate the 75th anniversary of India’s independence, the statistical achievements of a poor country in its early post-independent years should make us proud. But we must also ask why India’s statistical system no longer commands the respect it did in the republic’s early years.

This is the first of a five-part series on the founding fathers of India’s once-renowned statistical system.

Pramit Bhattacharya is a Chennai-based journalist. His Twitter handle is pramit_b

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