Anil Kumar Bhattacharya

Anil Kumar Bhattacharya (also spelled Anil Kumar Bhattacharyya, Bengali: অনিল কুমার ভট্টাচার্য) (1 April 1915 – 17 July 1996) was an Indian statistician who worked at the Indian Statistical Institute founded by P C Mahalanobis in the 1930s and early 40s. He made fundamental contributions to multivariate statistics, particularly for his measure of similarity between two multinomial distributions, known as the Bhattacharya coefficient, based on which he defined a metric, the Bhattacharya distance. This measure is widely used in comparing statistical samples in biology, physics, computer science, etc.

Distance between statistical distributions had been addressed in 1936 by Bhattacharyya's mentor, Mahalanobis, who proposed the D² metric, now known as Mahalanobis distance. Subsequently Bhattacharya defined a cosine metric for distance between distributions, in a Calcutta Mathematical Society paper in 1943, expanding on some of the results in another paper in Sankhya in 1947. Bhattacharyya's two major research concerns were the measurement of divergence between two probability distributions and the setting of lower bounds to the variance of an unbiased estimator.