P C Mahalanobis: India’s Numbers Man

He was a physicist by training, a statistician by instinct and an economist by conviction. He founded one of the first institutes in the world dedicated to the subject of statistics and was instrumental in formulating India’s Second Five-Year Plan. Prasanta Chandra Mahalanobis, or ‘PCM’, as he was fondly referred to by his colleagues, wore many hats. Here’s the story of this man of numbers:

Mahalanobis was born on 29th June 1893 into a wealthy family of intellectuals and social reformers in the erstwhile Bengal Presidency. After graduating with honours in physics from Presidency College, Calcutta, in 1912, he moved to England to study physics and mathematics at the University of Cambridge. Here, he came across Biometrika, a peer-reviewed scientific journal with a focus on theoretical statistics that piqued his interest in the subject. Soon he started researching statistical problems relating to agriculture, biology, meteorology and anthropometry.

On his return to India in 1915, Mahalanobis started teaching physics at his alma mater, Presidency College. But alongside that, he started an informal group of people interested in statistics to pursue the subject academically. When Rabindranath Tagore, a friend of Mahalanobis, learnt of his interest, he introduced him to Brajendranath Seal, a scholar and educator who asked the 24-year-old Mahalanobis to analyse the exam records of Calcutta University.

Mahalanobis was very curious about racial biometrics and anthropometry (the scientific study of the measurements and proportions of the human body). So when N Annandale, the then director of the Zoological and Anthropological Survey of India, provided PCM with a dataset of about 300 Anglo-Indians, he developed a statistical tool which he used to measure what he called “caste distances”.

He wrote in his paper titled Analysis of Race Mixture in Bengal (1925), “How are… Anglo-Indians… related to the different caste groups of Bengal?... Are they more closely allied with the Hindus or with the Mahomedans?” He measured the facial features of the people, the length and breadth of their face, the size of their nose, etc and compared these individual physical traits before combining them to produce a relative value.

This study was instrumental in initiating his more than decade-long research on anthropometric data, resulting in the theorizing of the ‘Mahalanobis distance’, his most notable research contribution. This statistical measure is often used to compare two different data sets and applied in studies of population distribution.

Mahalanobis also analysed data regarding flood control in North Bengal and Odisha, which later formed the basis for the construction of the Hirakud Dam on the Mahanadi River.

Within no time, the work of the small, informal group Mahalanobis had got together led to the establishment of the Indian Statistical Institute (ISI) in 1931, which had an annual budget of less than Rs 250. Mahalanobis believed, “Statistics must have a clearly defined purpose, one aspect of which is scientific advancement and the other human welfare and national development.”

The ISI grew over time and conducted research into diverse subjects including biochemistry, crop science, human genetics, psychometry, pre-census and economics. The Mahalanobis-led ISI conducted some wonderful data analyses and large-scale surveys like the impact of the 1943 Bengal Famine, rural indebtedness, tea-drinking habits, crop yield estimation, family budgets and the circulation of rupee coins.

This attracted the attention of Jawaharlal Nehru, who asked Mahalanobis to be a part of Independent India’s Planning Commission and later outline the Second Five Year Plan (1956-1961). The Second Plan thus followed what came to be known as the ‘Mahalanobis Model’. It focused on the development of the public sector and rapid Industrialisation.

For his pioneering work, Mahalanobis was awarded the Padma Vibhushan in 1968 and in his honour, his birthday is observed as National Statistics Day every year.

– DID YOU KNOW?

The first English translation of Albert Einstein and H Minkowski's famous German paper The Principle of Relativity was undertaken by Indian scientists S N Bose and Meghnad Saha (with an introduction by P C Mahalanobis) and published in 1920.