(i) Index of concentration is the proportion of the population living in each state or union territory to the total population of India.
(ii) Index concentration is a very useful method to understand the uneven nature of distribution of population.
For example, the population of Uttar Pradesh according to 2001 census was 166 million whereas total population of India in the same year was 1027 million. So, the index of concentration for U.P. in 2001 was : \(\frac {166}{1027} \) x 100 = 16.16