The three economic approaches to migration give primacy to the economic aspects of migration. They discuss how these aspects associated with the place of origin and destination regulates the movement of population, what pattern the movement follows. One of the economic approaches is the theory about the empirically and mathematically verified generalized patterns of migration. It originates from the contributions made by E.G Ravenstein.His laws of migration appeared during the year 1885-89.He published two famous and classic studies in 1885 and 1889 on the laws of migration in which he made empirical generalizations regarding patterns of migration. The following are the basic generations that he made.
The migration process is predominantly short distance The volume of migration decreases with distance. As the distance from the center of absorption increases, the volume of migration decreases. This implies that the role of migration is inversely proportional to the distance between the place of origin and the destination.
In most cases long distance migration proceeds to the greatest centres of commerce and industry. This implies that the rate of migration is directly proportional to the available opportunities at the places of origin and at the place of destination. The migrants who travel long distances will tend to move to nearby towns and then gravitate towards rapidly growing cities depending on available opportunities. This generalization gives rise to the gravity model of migration. According to this model the movement of population gravitates around the centres of socio-economic opportunities that are referred to as the factors of attractiveness. The availability of opportunities or propensities determines migration. The rural and urban differences in opportunities or differences within a region motivate people to move out for better opportunities to improve their conditions for living. The natives of towns are less mobile than the natives of villages.
There are a number of factors of migration but the economic motive always predominates in the matrix of factors as seen by Ravenstein.
The second approach under the economic perspective is the situation specific push and pulls factors analysis. It is an alternative model of migration. This approach is not concerned with empirically rested generalizations. It is situation-oriented approach dealing with socio-economic differentials existing at the place of origin and at the place of destination. Those differentials determine the migratory movement. The pull-push hypothesis is the central thrust of this approach. According to this view point migration is the result of the interplay between the expulsive forces at the place of origin and the attractive forces at the place of destination. The approach takes into account all possible factors that determine the movement of population. The most prominent name associated with this approach is Everett S Lee .He acknowledges the relevance of Ravenstein's theory of migration. He identifies the factors of migration and examines the volume of migration and the characteristic of migrants. Migration is a source of permanent or semi permanent change of residence. It may of short or long duration. The act of migration involves the place of origin, the place of destination and the set of intervening opportunities that affect migration.
The push and pull factors and their effects vary by region and by factors of age, education, occupation, class, caste, tribe, ethnicity, region and religion etc. The roles of these factors or individuals traits differ from the place of origin and to the place of destination but according to Lee there are certain common factors of similar reaction. People may like to move from one place to another for better education, higher wages, more job opportunities and better living conditions.The third economic approach under the economic perspective is the cost and benefit model of migration. This approach also gives primacy to the economic factors. The most prominent name associated with this is M.P Todaro.He defines the cost of migration as the moving cost or money available to move, travel and afford the costs of living at the destination. It also refers to the costs of searching and getting training for new jobs. The cost of migration also includes the psychic costs and temporary cost of staying without any job at the place of destination.
Migration is the interplay between the costs of migration and benefits of migration. If the migrant finds that the opportunities at a given place will maximize his expected gains in terms of actual income she/he decides to migrate. The central premise of Todaro's model is that the decision to migrate is taken by people on the basis of their assessment of the opportunities available to them in rural and urban areas. There is an element of subjectivity as an individual makes a subjective assessment of the objective opportunities at a given place to maximize expected benefits from migration taking into account the costs of migration and earning at the source of migration. There is always a basis of permanent income calculation in the mind of migrant.