On June 29, 1893, Indian statistician Prasanta Chandra Mahalanobis was born. Mahalanobis is best remembered for the Mahalanobis distance, a statistical measure and for being one of the members of the first Planning commission of free India. He also made pioneering studies in anthropometry in India. He also devised fractile graphical analysis to study socioeconomic conditions. He applied statistics to issues of crop yields and planning for flood control.
Prasanta Chandra Mahalanobis earned his Bachelor of Science degree in 1912 and then left for England one year later in order to study at the University of London. Mahalanobis missed a train and stayed with a friend at King’s College, Cambridge. He was so impressed with the college that he decided to join it. After graduating, he was introduced to the journal Biometrika which he took with him to India. The journal sparked his enthusiasm for statistical problems in meteorology and anthropology.
In 1920, Mahalanobis met with the director of the Zoological Survey of India Nelson Annandale at a session of the Indian Science Congress led to Annandale asking him to analyse anthropometric measurements of Anglo-Indians in Calcutta. Mahalanobis intended to examine what factors influence the formation of European and Indian marriages. With the help of Annandale’s data collection and the caste specific measurements made by Herbert Risley, Mahalanobis found out that the sample represented a mix of Europeans mainly with people from Bengal and Punjab but not with those from the Northwest Frontier Provinces or from Chhota Nagpur. Further, he discovered that the intermixture more frequently involved the higher castes than the lower ones. Prasanta Chandra Mahalanobis explained his analysis in his paper published in 1922. While studying the topic, Mahalanobis found a way of comparing and grouping populations using a multivariate distance measure. This measure, denoted ‘D2’ and now eponymously named Mahalanobis distance, is independent of measurement scale.
At the Presidency College, Calcutta an informal group of scientists interested in statistics formed in the Statistical Laboratory. In 1931, Prasanta Chandra Mahalanobis, Nikhil Ranjan Sen, and Sir R. N. Mukherji established the Indian Statistical Institute, which was registered as a non-profit distributing learned society one year later. In 1959, the institute was declared as an institute of national importance and a deemed university.
Prasanta Chandra Mahalanobis is well known for his large-scale sample surveys. He introduced the concept of pilot surveys and advocated the usefulness of sampling methods. For instance, Mahalanobis worked on topics like consumer expenditure, tea-drinking habits, public opinion, crop acreage and plant disease. He further discovered a method for estimating crop yields which involved statisticians sampling in the fields by cutting crops in a circle of diameter 4 feet.
References and Further Reading:
- A Scientific Take on the Indian National Identity Through Mahalanobis’s Profiloscope at The Wire
- Pransanta Chandra Mahalanobis at Britannica Online
- Pransanta Chandra Mahalanobis Career and Major Works