Remembering Prasanta Chandra Mahalanobis

This article reached us before June 29, Prof Mahalanobis’ birthday, but could not be used earlier due to unavoidable reasons.

Various statistical activities, such as crop-cutting surveys, socio-economic surveys, economic census, agriculture census, demographic census etc. being conducted in India are well known worldwide for their size and technical efficacy. Data captured through these surveys and censuses are utilised to ensure planned development and formulating policies for economic growth. Collection, tabulation and analysis of development statistics are primarily done by statisticians. Though people are aware of many of these statistical activities and organisations or agencies involved in accomplishing them, knowledge about the achievements and contributions of statisticians, that is, those who raised these strong pillars of development, is utterly limited. This is because of two main reasons. First, very few people prefer opting statistics as a career due to the fact that they will have to deal only with data and information throughout their life. The general human response is another reason since an entertaining movie is greatly accepted but efforts put in creating an artistic masterpiece are rarely publicised. Despite this, it is an established fact that a star performer always gets recognised. He shines in the sky of his own domain. In the Indian statistical universe too there is a star who not only established the base for the Indian statistical system putting in place the necessary infrastructure and suggesting strategic steps for planning but also showed the path to the world with his remarkable vision for statistics.

This bright star statistician, Professor Prasanta Chandra Mahalanobis, once again luminously shone in the horizon in 2007 when his birthday on June 29 was celebrated by the Centre and States declaring it as ‘Statistics Day’. A notification to this effect was published in the Gazette of India (Extraordinary, Part I—Section 1, Number 146) on June 5, 2007 and thereafter the Ministry of Statistics and Programme Implementation issued an office order on June 6, 2007. The first Statistics Day was inaugurated by the Prime Minister, Dr Manmohan Singh, who released a brochure, ‘Statistics Day – 2007’, on the occasion. A national award in statistics (2006-07), initiated in the honour of another great statistician of India, Professor C.R. Rao, was presented by G.K. Vasan, the Minister of State (independent charge) to Professor Ayendra Nath Basu. Joint recipients of the Mahalanobis Award (2007), Professor S.C. Tendulkar, Chairman of the National Statistical Commission, and Professor I.P. David of Philippines addressed the august gathering dwelling on the achievements and contributions of Professor Mahalanobis. The second Statistics Day was inaugurated by Pranab Mukherjee, the Minister of External Affairs, on June 29, 2008 in a programme presided by G.K. Vasan, the Minister of State (independent charge), Ministry of Statistics and Programme Implementation. Mukherjee also unveiled version-2.0 of DevInfo, a collection of development statistics and information prepared through joint efforts of the Ministry of Statistics and Programme Implementation and UNICEF. During both these programmes prizes were distributed to students of post-graduate who were winners of essay competitions organised by the Central Statistics Organisation. On the occasion of the third Statistics Day, to be celebrated this year on June 29, the birthday of Professor Mahalanobis, one gets a chance to pay tribute and homage to Professor Mahalanobis remembering his world-renowned achievements and contributions in raising the Indian statistical system.

Professor Mahalanobis was born on June 29, 1883 in a progressive Brahmo family of Kolkata. After completing his primary education from Brahmo Boys School, Kolkata in 1908, he did his Honours in Physics from Presidency College, Kolkata in the year 1912. Thereafter he proceeded to King’s College, Cambridge for higher education and completed ‘Tripos in Natural Sciences’ in 1915. He returned to India in the same year and preferred joining Presidency College as a Professor in Physics. He retired in 1948 as the Principal of Presidency College. However, from time-to-time he also served at various prestigious positions such as a Meteorologist (1922-26), a Member of the Planning Commission (1953-68) and the Chief Executive of the Indian Statistical Institute (till the last day of his life).

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Although principally he was a physicist, his fascination towards statistics was by chance, itself the basis of the Theory of Probability. During his stay at Cambridge, his tutor, W.H. Macaulay, suggested to him to go through Biometrika, a journal edited by Karl Pearson. He got so impressed with Biometrika that while returning India he brought a complete set of its available volumes. In 1920 he met Nelson Annandale, Director of the Zoological Survey of India, who persuaded him to analyse anthropological measurements collected on the Anglo-Indians of Kolkata. This meeting resulted in the publication of his first scientific research paper in 1922. He coined D2-Statistics, which is known as Mahalanobis Distance Measure, and used it for divergence based grouping.

In 1922, northern Bengal was badly hit by a drastic flood, which turned his attention towards extensive analysis of 50 years’ statistics on rain and flood. Based on this analysis he suggested a low cost plan to drain flood water, contrasting with the views of many engineering experts. However, on being implemented his plan was found fruitful and workable. While estimating possible error in the results of agricultural experiments in 1924, he met Sir Ronald A. Fisher, who is known as the Father of Statistics. This meeting resulted in a life-long friendship. His crop-cutting surveys for estimation of agricultural production are still relevant due to their design. He initiated sample surveys in 1937 for estimating production and area under jute. He succeeded in proving scientifically that sometimes survey results do exhibit a pattern similar to the complete enumeration or census. Moreover, these could be attained with lesser cost and time. This particular achievement of his became a boon to statistics in the form of Large Sample Surveys. He conducted various surveys on consumer-expenditure, tea-drinking habits, public opinion, plant diseases etc. in the period 1937-44. Pilot surveys which were conceptualised and conducted by Professor Mahalanobis later on become the base for sequential sampling. This fact was revealed in a book by Abraham Wald, who was the developer of sequential sampling methods. Due to his creditable achievements in the field of sampling surveys Professor Mahalanobis was elected as the Chairman of the United Nations Sub-Commission on Statistical Sampling in 1947. He held this position for the next five years.

He was bestowed with various prestigious awards and a number of honourable degrees were also conferred on him. He received the Weldon Medal (1944) from Oxford University and Padma Vibhushan (1968) from the Government of India. He was elected Fellow of the Royal Society of Landon (1945), President of the Indian Science Congress (1950), Fellow of Econometric Society of America (1951), Fellow of the Pakistan Statistical Association (1952), Honorary Fellow of the Royal Statistical Society of England (1954), Foreign Member of the Soviet Academy of Sciences (1959) and Fellow of the American Statistical Association (1961).

A laboratory, which was established in his chamber at the Presidency College, Kolkata, witnessed the birth of Indian Statistical Institute (ISI) on December 17, 1931 when he held a meeting with P.N. Banerjee, Nikhil Ranjan Sen and Sir R.N. Mukherjee. Later the ISI was formally registered on April 28, 1932 under the Societies, Registration Act (1860). Initially this institute functioned from the Physics Department of the college. However, with passage of time other statisticians such as S.S. Bose, J.M. Sengupta, R.C. Bose, S.N. Roy, K.R. Nair, D.B. Lehari and many more got associated with Professor Mahalanobis and the Institute expanded tremendously gaining international repute. Professor Mahalanobis successfully attracted specialist statisticians from different disciplines, such as Professors C.R. Rao, G. Kallianpur, S.K. Mitra, K.R. Parthasarathi, S.R.S. Varadhan, J.B.S. Haldane, R.A. Fisher and A.N. Kolmogrov, to visit the Institute as part of the guest faculty. He started publication of Sankhya, a statistical journal of the Institute, in 1933. His continuous and sustained efforts made the ISI an institution of academic excellence and international repute. The Government of India also hailed the achievements of the Institute by passing the Indian Statistical Institute Act in 1959, thereby recognising it as an Institute of national importance and giving it the status of a Deemed University.

After independence in 1947, there appeared a genuine need of establishing a fundamentally pure statistical system to ensure the socio-economic development of the country. Professor Mahalanobis was appointed the Honorary Statistical Advisor by the Government of India in 1949. The Central Statistical Unit was established under his guidance and supervision. It later, in 1951, became the Central Statistical Organisation (CSO). The prime objective of this organisation was to coordinate with various Ministries which were engaged in statistical activities and help those providing necessary technical inputs. However, persisting data-gaps in the field of socio-economic progress simultaneously paved the way for another organisation. Consequently, on the recommen-dation of the National Income Committee, which was chaired by Professor Mahalanobis, the National Sample Survey came into existence in 1950 with its mandate to capture data conducting socio-economic surveys in various fields. This unit finally got established as the National Sample Survey Organisation (NSSO) in 1970.

Due to his vision and modern work-style Professor Mahalanobis had tremendous support and help from Pandit Jawaharlal Nehru. Being a Member of the Planning Commission he prepared the Second Plan document in 1954 at the ISI itself. He visualised that development models of advanced countries were not suitable for India and, therefore, he conceptualised a two-sector development model for India. His model, which was technically different from Leontief’s Input-Output model, could ensure faster industrialisation in India. Pandit Nehru invited Chou-en-Lai, the Prime Minister of China, and Ho-Chi-Minh, the President of Vietnam, to visit India and specifically the ISI. Chou and Ho visited the ISI on September 9, 1956 and February 13, 1958 respectively. Chou was very impressed and he instantaneously assured Professor Mahalanobis of sending statisticians from his country for study and training in the Institute. This way the ISI opened up a newer way of academic-bridging between India and neighbouring countries.

Professor Mahalanobis evolved a precious four-step strategy while he motivated statisticians to contribute for growth and development of the nation. According to him, they should first analyse and extract results from data collected through properly designed surveys. In the next step, these results should be used for selecting suitable and beneficial development schemes. During implementation of a scheme of choice, works done under it should be analysed for their concurrence with pre-set objectives. Finally, mid-term corrections should be done whenever conducted works are not found in consonance with the goals of the scheme. This particular approach suggested by him in respect of Plan implementation has stood the test of time and it is relevant even today. This brings out his farsightedness and ability to conceptualise. He was a complete statistician in himself. This ‘Renaissance-man and Scientist’ breathed his last on June 28, 1972. He still shines bright in the statistical firmament and shows the path to various statisticians, economists and planners the world over.

The author is the Joint Director, Directorate of Economics and Statistics, Government of Uttarakhand.