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\noindent{\bf Prasanta Chandra MAHALANOBIS}\\
b. 29 June 1893 - d. 28 June 1972
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\noindent{\bf Summary.}  A father figure in Indian Statistics, 
Mahalanobis is well-known for his $D^2$ statistic and pioneering 
contributions to large scale sample surveys. He is also 
remembered for his historic role in modernizing the Indian 
Statistical System, applications including dams and 5 year economic 
plans and contributions to Statistical Systems of other countries as 
Chair of the UN Subcommission on Statistics.
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A biographer of Mahalanobis has desribed him as a Renaissance man
and scientist.  He could also be described as a child of a
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 Manalanobis's grandfather founded, with others, an
organization called the {\it Sadharan Brahmo Samaj} , which was to
become a torch-bearer of the Bengal Renaissance.  His father,
Probodh 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.

Prasanta Chandra completed his schooling in Calcutta in 1908.  In
1912, he graduated with honors in Physics from Presidency College,
Calcutta.  He went to England in 1915 and completed Tripos in
Mathematics and Physics from Kings 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 fellowship.
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.

Just before Mahalanobis left Cambridge, his tutor, W.H. Macaulay,
drew his attention to {\it Biometrika}.  Mahalanobis found the articles
interesting, purchased the whole set of available volumes and
brought back to Calcutta.  A window was opened to a new area of
science, permanently changing the direction of his life.

Among his mentors in Calcutta was Acharya Brojendranath Seal, a
philosopher and an encyclopaedist, 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 Annandale, the then Director of Zoological
and Anthorpological Survey of India, who had collected
anthropometric measurements on Anglo-Indians of Calcutta. Annandale
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 {\it 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 meteorological 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 was
located about 4 kms. above sea-level.  Subsequently, he was
appointed Meteorologist in the Alipore Observatory and he held this
post from 1922 to 1926.

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 (q.v.).  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.

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.

In 1927, Mahalanobis spent a few months in Karl Pearson's (q.v.)
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
biological affinities.  He noted several shortcomings of the CRL
and in 1930 published his seminal paper on the $D^2$-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
$D^2$-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.

Mahalanobis's contributions to large scale sample surveys are among
his most significant and lasting gifts to statistics.  He started
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.
Untimately 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 sub-samples 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
random-ness and representativeness of a sample, which remain
relevant and challenging even today.  He was elected Chairman of
the United Nations Sub-Commission on Statistical Sampling in 1947,
and held this post until 1951.  His tireless advocacy of the
usefulness of sample surveys resulted in the final recommendation
of this Sub-commision 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.

Mahalanobis believed that statistics in 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 fallen
out of favour, the need for planning in the initial stages 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.

The year 1931 marks a watershed in the development of statistics in
India.  From the fledgling Statistical Laboratory formed in the
early 1920's 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, Samarendranth Roy and C. Radhakrishna Rao.  He 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
National Importance".

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 helped in the 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.

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 honors and awards.  He received the
highest national honor, {\it Padma Vibhusan} , from the President
of India in 1968.

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 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
systematizations.  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 systematization are apparent in his work on
large-scale sample surveys and planning.  For him, theory grew out
of a practical need and thus influenced subsequent practical work.
He had nothing but contempt for irrelevant, poorly conceived
abstraction which he would dismiss as ``aerodynamics in a viscous
fluid".

As a science organizer (and a thinker on organization of science),
Mahalanobis was one of the very best of our time.  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, Pandit Jawaharlal Nehru, and many
other national leaders, Mahalanobis was never a part of any
establishment.  He disliked all forms of bureaucracy in Indian
science.  He was an organizer with vision who loved innovation and
adventure and was ready to take risks.  He was an entrepreneur in
science.
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\noindent{\bf Bibliography}

\noindent Ghosh, J.K. (1994). Mahalanobis and the art and science
of statistics: the early days. {\it Indian Journal of the History
of Science} {\bf 29}, 89 - 98.

\noindent Mahalanobis, A. (1983). {\it Prasanta Chandra Mahalanobis}.
National Book Trust, New Delhi.

\noindent Rao, C.R. (1973). Prasanta Chandra Mahalanobis, 1893-1973.
{\it Biographical Memoirs of Fellows of the Royal Society} {\bf 19},
455-492.

\noindent Rudra, A. (1996). {\it Prasanta Chandra Mahalanobis: A
Biography}. Oxford University Press, Delhi.
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\hfill{J.K. Ghosh}


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