C. R. Rao FRS
Rao in 2012
Born	Calyampudi Radhakrishna Rao (1920-09-10)10 September 1920 Hoovina Hadagali, Madras Presidency, British India (present day Vijayanagara, Karnataka, India)[1][2]
Died	22 August 2023(2023-08-22) (aged 102) Buffalo, New York, U.S.
Citizenship	Indian (until 1995) American (1995–2023)[3]
Education	Andhra University (MA) University of Calcutta (MA) King's College, Cambridge (PhD, DSc)
Known for	Cramér–Rao bound Rao–Blackwell theorem Orthogonal arrays Score test
Awards	Padma Vibhushan National Medal of Science (2001) S. S. Bhatnagar Prize Guy Medal (Silver 1965, Gold 2011) International Prize in Statistics (2023)
Scientific career
Fields	Mathematics and Statistics
Institutions	Indian Statistical Institute Cambridge University Pennsylvania State University University at Buffalo
Thesis	Statistical Problems of Biological Classifications  (1948)
Doctoral advisor	Ronald Fisher
Doctoral students	S. R. Srinivasa Varadhan K. R. Parthasarathy Veeravalli S. Varadarajan R. Ranga Rao Debabrata Basu Radha Laha Ravindra Khattree Thiruvenkatachari Parthasarathy Dabeeru C. Rao Sreenivasa Rao Jammalamadaka U. S. R. Murty

Prof. Calyampudi Radhakrishna Rao FRS (10 September 1920 – 22 August 2023) was an Indian-American mathematician and statistician.^[4] He was professor emeritus at Pennsylvania State University and research professor at the University at Buffalo. Rao was honoured by numerous colloquia, honorary degrees, and festschrifts and was awarded the US National Medal of Science in 2002.^[5] The American Statistical Association has described him as "a living legend" whose work has influenced not just statistics, but has had far reaching implications for fields as varied as economics, genetics, anthropology, geology, national planning, demography, biometry, and medicine."^[5] The Times of India listed Rao as one of the top 10 Indian scientists of all time.^[6]

In 2023, Rao was awarded the International Prize in Statistics,^[7] an award often touted as the "statistics' equivalent of the Nobel Prize".^[8] Rao was also a Senior Policy and Statistics advisor for the Indian Heart Association non-profit focused on raising South Asian cardiovascular disease awareness.^[9]

C. R. Rao was the eighth of the ten children born to a Telugu Velama family^[10][1] in Hoovina Hadagali, Bellary, Madras Presidency, Britain ruled India (now in Vijayanagara, Karnataka, India). His schooling was completed in Gudur, Nuzvid, Nandigama, and Visakhapatnam, all in the present state of Andhra Pradesh.^[2] He received an MSc in mathematics from Andhra University and an MA in statistics from Calcutta University in 1943.^[5] He obtained a PhD degree at King's College, Cambridge, under R. A. Fisher in 1948, to which he added a DSc degree, also from Cambridge, in 1965.^{[citation needed]}

Rao first worked at the Indian Statistical Institute and the Anthropological Museum in Cambridge. Later he held several important positions, as the Director of the Indian Statistical Institute, Jawaharlal Nehru Professor and National Professor in India, University Professor at the University of Pittsburgh and Eberly Professor and Chair of Statistics and Director of the Center for Multivariate Analysis at Pennsylvania State University.^[11]

As Head and later Director of the Research and Training School at the Indian Statistical Institute, India for a period of over 40 years, Rao developed research and training programs and produced several leaders in the field of Mathematics. On the basis of Rao's recommendation, the Asian Statistical Institute (ASI), now known as the Statistical Institute for Asia and Pacific, was established in Tokyo to provide training to statisticians working in government and industrial organisations.^[12]

Among his best-known discoveries are the Cramér–Rao bound and the Rao–Blackwell theorem both related to the quality of estimators.^[13] Other areas he worked in include multivariate analysis, estimation theory, and differential geometry. His other contributions include the Fisher–Rao theorem, Rao distance, and orthogonal arrays. He was the author of 15 books^[11] and authored over 400 journal publications.

Rao received 38 honorary doctoral degrees from universities in 19 countries around the world and numerous awards and medals for his contributions to statistics and science. He was a member of eight National Academies in India, the United Kingdom, the United States, and Italy. Rao was awarded the United States National Medal of Science, that nation's highest award for lifetime achievement in fields of scientific research, in June 2002. He was given the India Science Award in 2010, the highest honour conferred by the government of India in a scientific domain. He was most recently honoured with his 38th honorary doctorate by the Indian Institute of Technology, Kharagpur, on 26 July 2014 for "his contributions to the foundations of modern statistics through the introduction of concepts such as Cramér–Rao inequality, Rao–Blackwellization, Rao distance, Rao measure, and for introducing the idea of orthogonal arrays for the industry to design high-quality products."

Rao was the President of the International Statistical Institute, Institute of Mathematical Statistics (USA), and the International Biometric Society. He was inducted into the Hall of Fame of India's National Institution for Quality and Reliability (Chennai Branch) for his contribution to industrial statistics and the promotion of quality control programs in industries.

The Journal of Quantitative Economics published a special issue in Rao's honour in 1991: "Dr. Rao is a very distinguished scientist and a highly eminent statistician of our time. His contributions to statistical theory and applications are well known, and many of his results, which bear his name, are included in the curriculum of courses in statistics at bachelor's and master's level all over the world. He was an inspiring teacher and has guided the research work of numerous students in all areas of statistics. His early work had greatly influenced the course of statistical research during the last four decades. One of the purposes of this special issue is to recognise Dr. Rao's own contributions to econometrics and acknowledge his major role in the development of econometric research in India."

Rao died in Buffalo, New York on 22 August 2023, aged 102.^{[14][15][16][17]}

Obituaries describing his professional contributions and impact on the society have been published in the IMS Bulletin [1] and Nature [2].

• 2023 International Prize in Statistics

• Nalini Krishnankutty, 1996. Putting Chance to Work: A Life in Statistics: A Biography of C. R. Rao.
• किशोर खनाल, 2080. "विश्वविख्यात प्रोफेसर सीआर रावको सम्झनामा". विश्वविख्यात प्रोफेसर सीआर रावको सम्झनामा
• Kishor Khanal and Shankar Prasad Khanal, 2023. " An interview with Professor C.R. Rao on the occasion of his 100th birthday". [3]

• Calyampudi Radhakrishnan Rao. University of Minnesota Morris
• Statisticians in History: Calyampudi R. Rao" Archived 3 March 2016 at the Wayback Machine. American Statistical Association
• "Prof. C R Rao : An Eminent Statistician" By Bibhuprasad Mohapatra Archived 24 September 2015 at the Wayback Machine. Govt. of Odisha.

For the Cramér–Rao inequality and the Rao–Blackwell theorem see the relevant entries on

• Earliest Known Uses of Some of the Words of Mathematics

For Rao contribution to information geometry

• Cramer-Rao Lower Bound and Information Geometry

Photograph of Rao with Harald Cramér in 1978

• C. R. Rao from the PORTRAITS OF STATISTICIANS
• President George Bush awarding Rao the National Medal of Science