GUWAHATI, May 5 ? The size of migration of people to Assam between 1951 and 1991 was 28,75,492 and of this, the size of the illegal foreign migrants to the State, during the period, was 12,98,754. This was revealed by a study conducted by the Omeo Kumar Das Institute of Social Change and Development (OKDISCD) here. The study entitled ?Migration to Assam : 1951-1991?, was conducted by a team of experts comprising Prof Atul Goswami, Prof Homeswar Goswami and Dr Anil Saikia on behalf of the OKDISCD. The study, however, revealed that during the said period the estimated number of total foreign migrants who entered the State was 19,83,755 and of them, 6,85,001 were legal migrants as they reported their place of birth. The OKDISCD undertook the study with the primary objective of providing a scientific explanation of the growth of population in the State during 1951-1991 in terms of various components of population growth, viz, fertility, mortality and migration, with focus on migration.
The exercise was carried out decade-wise and age group-wise. This was done so as to set at rest the speculations on the issue of the actual size of inter-state as well as international migrants to the State between 1951 and 1991. The study is based on census population data and Sample Registration System (SRS) estimates of fertility and mortality rates. But it relied more on that indirect methods like the residual method or vital statistics method and the survival rate method for arriving at the conclusion. Using the residual method or vital statistics method, the experts could come to the conclusion that migration in a second census is equal to the difference of the differences between the two consecutive census populations and the total births and deaths during the intercensal period. Alternatively, they observed, population of the second census is equal to the sum of the first census population and the difference of births and deaths and migration, if any, between the two censuses.
The survival rate method is commonly used in underdeveloped countries which are usually deficient in accurate statistical data, because it does not demand accurate vital statistics. It is also used in developed countries partly because it yields estimates of net migration by age and sex. While arriving at the conclusion thus, the experts observed that though the persons born elsewhere in India usually reported their place of birth correctly, the foreign migrants who entered illegally, never disclosed their actual place of birth to avoid deportation.
Therefore, the experts said, while the census data on internal migration can safely be taken as accurate, those of international migration are far from being so. Therefore, they said, from the total number of estimated immigrants of Assam during each period (i.e. 1951- ?61, 1961- ?71 and 1971- ?91), the number of internal migrants as found in the corresponding census report, was deducted to arrive at the total number of foreign migrants in Assam in each period.