Question

1. Describe the four theories/models of migration and state their strengths and limitations.

Answer 1

The theories are

1. Ravenstein’s Laws of Migration predicts:
i) Inverse relation between distance and volume of migration
ii) Step wise migration
iii) Every forward trend to lead to reverse trend
iv) Greater rural migration that urban and rural migration to urban centres
v) Selective migration comprising working age population mainly due to economic reasons
vi) Migration increases with ecnomic diversification and improvement in transport facilities
Strength and weakness- Though i, v and vi have been proven to be correct, other predictions like ii and iii are more difficult to verify, and the nature pf migration in developed economies may also not follow iv.

2. Gravity Model:
where MI_ij is the volume of migration between the centres i and j, P_i and P _i are population size of the two centres, d_ij is the distance between them. K is a constant.
This model predicts that migration is not only a function of distance (inverse) but also populaiton.
Strength and weakness- Though this model predicted the development, lure of urban centres as migrant destinations and retail trade, it is criticized for its generalization based on population and a linear measure of transportation discarding the advancements of transport facilities.

3. Stouffer’s Theory of Mobility:
where Xo is the number of out-migrants from city 1; Y is the number of migrants moving from city 1 to city 2, Xi is the number of opportunities in city 2, X₁ is the number of opportunities intervening between city 1 and city 2, Xc is the number of migrants competing for opportunities in city 2, and k is a constant
This formulates that migration is as much a result of attraction to other city as repulsion from one's own. It relies on the premise that migration is proportional to the number of opportunities at that distance and inversely proportional to the number of intervening opportunities.
Strength and weakness- Though this model incorporates various factors and relies on empirical estimation for the parameters, its total discar of distance is severely criticized and is contrast to Zipf's Inverse distance Law.

4. Lee’s Theory
This theory divides factors causing migrations into two groups of factors: Push and pull factors. Lee theorized that its not only the factors at origin and destination that play roles in migration decision making but the perception of these factors is also critical things that result in migration. The perception depends on personal characteristics like personal sensitivities, intelligence, and awareness in evaluating the situation of origin and destination factors. Moreover, its not only about the comparison of the factors but there is an inertia that acts as an obstacle. Lee developed factors that lead to spatial mobility and proposed hypotheses on volume, streams and counter streams of migration and characteristics of migration.
Strength and weakness- This is considered a path breaking model due to its formulation of the factors and explanatino of mmigration, however, there exists criticisms that it is difficult to determine factors at origin and destination and their perception among people. Also, intervening obstacles make it even more difficult to understand major influences and minor factors.