Prasanta Chandra Mahalanobis
A Child of Renaissance
(29 June 1893 - 28 June 1972)
A biographer of Mahalanobis has described him as
a renaissnce man and scientist. He could also be described as a child of
renaissance. In spirit, if not quite in time, his roots may be traced to
the Bengal Renaissance, a social and cultural awakening that shook the
province of Bengal in nineteenth century India. Prasanta Chandra
Mahalanobis's grandfather founded, with others, an organization called the
Sadharan Brahmo Samaj, which was to become a torch-bearer of the Bengal
Renaissance. His father, Prabodh Chandra, was an active member of this
organization. His mother, Nirodbasini, belonged to a family of
considerable academic achievements. Into this family, Prasanta Chandra was
born on 29 June, 1893.
His Formal Education
Prasanta Chandra completed his schooling in Calcutta in 1908. In 1912,
he graduated with honours in Physics from Presidency College, Calcutta. He
went to England in 1913 and completed Tripos in Mathematics and Physics
from King's College, Cambridge. In Part II of the Tripos, he was the only
candidate to get a first class in Physics. King's College awarded him a
senior research felllowship. Before starting his research, he came to
Calcutta for a short vacation, but never returned to England. The war
intervened. Also, he had found a teaching job and plenty of other
interesting things to do in Calcutta.
The Opening of a Window
Just before Mahalanobis left Cambridge, his tutor, W.H. Macaulay, drew
his attention to Biometrika. Mahalanobis found the articles
interesting, purchased the whole set of available volumes and brought
these back to Calcutta. A window was opened to a new area of science,
permanently changing the direction of his life.
His Early Statistical Work
Among his mentors in Calcutta was Acharya Brojendranath Seal, a
philosopher and an encyclopedist, who was also interested in Statistics.
Seal was to have a lasting influence on Mahalanobis's life and work. In
1917, Seal, who held the Chair of Philosophy in Calcutta University,
sought the help of Mahalanobis in analyzing examination results of the
University. Soon thereafter, Mahalanobis met Nelson Annadale, the then
Director of Zoological and Anthropological Survey of India, who had
collected anthropometric measurements on Anglo-Indians of Calcutta.
Annadale requested Mahalanobis to Analyze the data. The results of
statistical analyses of a portion of these data resulted in Mahalanobis's
first paper on statistics entitled 'Anthropological Observations on
Anglo-Indians of Calcutta, Part I: Male Stature', published in Records of
the Indian Museum in 1922. This paper attracted the attention of Sir
Gilbert Walker, Director General of Observatories, who requested
Mahalanobis to undertake a systematic study of some metrological problems.
This resulted in an important discovery by Mahalanobis that the region of
highest control for changes in weather on the surface of the earth is
located about 4 kilometers above sea-level. Subsequently, he was appointed
Meteorologist in the Alipore Observatory and he held this post from 1922
He Finds a Friend
Some of the early statistical studies he undertook were on experimental
designs in agriculture. In 1924, he made some important discoveries
pertaining to the probable error of results of agricultural experiments,
which put him in touch with R.A. Fisher. Later in 1926, he met Fisher at
the Rothamsted Experimental Station and a close personal relationship was
immediately established which lasted until Fisher's death.
Floods and Dams
At the request of the Indian Government, Mahalanobis undertook some
work on prevention of floods in various regions of the country. His
findings and recommendations, though often contrary to engineering wisdom
of the time, were accepted by the Government and resulted in alleviation
of the problem of flooding to a large extent.
Mahalanobis and His Distance
In 1927, Mahalanobis spent a few months in Karl Pearson's laboratory in
London, during which period he performed extensive statistical analyses of
anthropometric data and closely examined Pearson's Coefficient of Racial
Likeness (CRL) for measurement of bilogical affinities. He noted several
shortcomings of the CRL and in 1930 published his seminal paper on the D-square
statistic entitled 'Tests and Measures of Group Divergence'. Mahalanobis's
interest in anthropometry remained strong and two large-scale
anthropometric surveys were carried out under his direction in the United
Provinces and Bengal. Based primarily on the D-square statistic,
many of the important anthropological inferences drawn from the data
collected in these surveys have stood the test of time. For example, the
conclusion that Bengal Brahmins resemble other castes of Bengal more
closely than they resemble Brahmins from elsewhere in India has been
corroborated by many subsequent studies.
His Most Significant and Lasting Gift
Mahalanobis's contributions to large scale sample surveys are among his
most significant and lasting gifts to statistics. He stared his work on
sample surveys with estimation of area and yield of jute crop in Bengal in
1937. However, it was not easy for him to get these estimates accepted;
controversy between him and the advocates of complete enumeration
continued for over a decade. Ultimately he was able to demonstrate that
estimates based on sample surveys were often more accurate than those
based on complete enumeration, and that sample surveys could yield
estimates with small margins of error within a short time and at a smaller
cost than complete enumeration. He made many methodological contributions
to survey sampling that included optimal choice of sampling design using
variance and cost functions, and the technique of interpenetrating network
of subsamples for assessment and control of errors, especially
non-sampling errors, in surveys. The concept of pilot surveys was a
forerunner of sequential sampling developed by Abraham Wald, as
acknowledged by Wald in his book. In addition to introducing these
concepts, Mahalanobis raised important and difficult philosophical
questions on randomness and representativeness of a sample, which remain
relevant and challenging even today. He was elected Chairman of the United
Nations Subcommission on Statistical Sampling in 1947, and held the post
till 1951. His tireless advocation of the usefulness of sample surveys
resulted in the final recommendation of this subcommission that sampling
methods should be extended to all parts of the world. Mahalanobis received
the Weldon Medal from Oxford University in 1944 and was elected a Fellow
of the Royal Society, London, in 1945, for his fundamental contributions
to Statistics, particularly in the area of large-scale sample surveys.
He Plans for Economic Prosperity of the
Mahalanobis believed that statistics should be an integral part of the
dynamics of national planning. He was acutely aware of national problems
and national resources. He took a keen interest and played a key role in
formulating India's second five-year plan based on the four-sector model
developed by him. Broad sectoral allocations of employment, capital
investment and increment in national income were worked out and then split
into detailed targets. Even though national planning seems to have now
gone out of fashion, the need for planning in the initial stags of a
nation's development is still acknowledged and Mahalanobis's contributions
to Indian national planning continue to be held in high esteem by
economists. During the last decade of his life, he devised a statistical
method, fractile graphical analysis, for comparison of socio-economic
conditions of groups of people. This technique has now been used in many
other branches of science.
His Dream Comes True: ISI
Declared as an Institution of National
The year 1931 marks a watershed in the development of statistics in
India. From the fledgling Statistical Laboratory formed in the early 1920s
by Mahalanobis within the Physics department of Presidency College, he
founded the Indian Statistical Institute on 17 December, 1931. He
persuaded many bright young physicists and mathematicians to join the
Institute. They included Raj Chandra Bose, Samarendra Nath Roy and C.
Radhakrishna Rao. 'Professor', - as he was referred to by everyone in the
Institute, - and his wife, Nirmalkumari, poured in all they possessed to
establish the Institute on a firm footing. In 1959, by an act of the
Indian Parliament, the Institute was declared as an 'Institution of
Mahalanobis and the Statistical System
Mahalanobis's role as a planner prompted him to play a pioneering role
in the organized collection of official statistics. He established the
National Sample Survey in 1950 with the objective of providing
comprehensive statistics relating to all economic and social aspects on an
all-India basis. He also helped in setting up of the Central Statistical
Organization in India, an apex body for coordination of statistical
activities in India. He was instrumental in the establishment of formal
teaching of statistics in many Indian universities and also in the Indian
Statistical Institute. In collaboration with the International Statistical
Institute, he established an International Statistical Education Centre at
the Indian Statistical Institute.
Some Feathers in His Cap
Mahalanobis became the Honorary President of the International
Statistical Institute in 1957, and was elected a fellow of the American
Statistical Association in 1961. Throughout his career he received many
other academic honours and awards. He received the highest national honour,
Padma Vibhushan, from the President of India in 1968.
An Applied Statistician of the Highest
As a scientist Mahalanobis was, above all, a great applied
statistician. Statistics was to be used for better understanding and
reporting of scientific and engineering data and decision making for the
welfare of the society. In Mahalanobis's work on prevention of floods,
both aspects of statistics, namely, understanding and decision making,
come together. On the other hand, in his pioneering work on anthropometric
variation in India, it is the first aspect that dominates.
In his work as an applied statistician, Mahalanobis was very
innovative, often introducing new concepts or methodologies or
systemizations. His work on flood control combined innovative data
analysis, understanding and modeling natural phenomena, and a
systematization of the whole complex analysis which made his
recommendations so readily acceptable to the government. The same gift for
innovation and systemization are apparent in his work on large-scale
sample surveys and planning. For him, theory grew out of a practical need
and this influenced subsequent practical work. Innovation and very
concrete applications are the hallmark of the sort of applied statistics
that Mahalanobis practiced. He had nothing but contempt for irrelevant,
poorly conceived abstraction which he would dismiss as 'aerodynamics in a
As a science organizer (and a thinker on organization of science),
Mahalanobis was one of the very best of the twentieth century. The fact
that Indian contributions to statistics have been so noteworthy is due to
him, more than to anything else. In spite of being close to India's first
prime minister, Jawaharlal Nehru, and many other national leaders,
Mahalanobis was never a part of any establishment. He disliked all forms
of bureaucracy in science. He was an organizer with vision who loved
innovation and adventure and was ready to take risks.
Prasanta Chandra Mahalanobis was an entrepreneur in science.
For further reading:
J.K. (1994), Mahalanobis and the art and science of
statistics: The early days. Indian Journal of History of Science,
J.K. and Majumder, P.P. (1998) Mahalanobis, Prasanta Chandra.
In "Encyclopedia of Biostatistics" (Eds. P. Armitage
and T. Colton), John Wiley & Sons, Chichester, UK. Pp. 2372-2375.
Mahalanobis, A. (1983), Prasanta Chandra Mahalanobis.
National Book Trust, New Delhi.
Rao, C.R. (1973), Prasanta Chandra Mahalanobis, 1893-1972. Biographical
Memoirs of Fellows of The Royal Society, 19, 455-492.
Rudra, A. (1996), Prasanta Chandra Mahalanobis: A Biography.