In 1931, when Roy joined the Department of Applied Mathematics of
Rajabazar Science College at the University of Calcutta as a research associate, he used computing facilities at the newly established
Indian Statistical Institute, He was well known for his pioneering contribution to multivariate statistical analysis, mainly that of the Jacobians of complicated transformations for various exact distributions, rectangular coordinates and the Bartlett decomposition. His dissertation included the Post master's work at the Indian Statistical Institute where he worked under Mahalanobis. It was Bose who first went to the United States as a visiting professor at
Columbia University and then joined the
University of North Carolina at Chapel Hill in 1947. Roy followed suit by later joining him at the
University of North Carolina at Chapel Hill in the spring of 1950, after initially travelling to the United States to take up a Visiting Professorship of Statistics at
Columbia University in New York in the spring of 1949. In between this Roy returned to India and became Head of the Department of Statistics at the
University of Calcutta during the academic year 1949–50. To commemorate his Birth Centenary an International Conference on "Multivariate Statistical Methods in the 21st Century: The Legacy of Prof. S.N. Roy" was held at Kolkata, India during 28–29 December 2006. The Journal of Statistical Planning and Inference published a special issue for celebrating the Centennial of Birth of S. N. Roy. ==Personal life==