1, the more commonly used economic models of migration such as todaro migration model place exclusive emphasis on the income differential factor as the determinant of the decision to migrate i.e the should seek the higher paying urban job. Why such an analysis is not realistic in the context of the institutional and economic frame work of todays most developing nations.

There are several reasons why the income differential factor as the sole determinant of migration decisions may not be realistic in today's developing nations:

1. Lack of job opportunities: In many developing countries, the job market is often limited and competitive, which can make it difficult for individuals to find higher-paying jobs in urban areas. This can be due to high levels of unemployment, underemployment, or lack of skills training opportunities.

2. Informal economy: In many developing countries, a significant portion of the workforce operates in the informal economy, which may not offer the same salary and benefits as formal sector jobs. This can make the income differential between rural and urban areas less pronounced.

3. High cost of living: Urban areas in developing countries often have a high cost of living, including expensive housing, transportation, and healthcare. This can erode the economic benefits of migrating to the city for higher-paying jobs.

4. Social ties and cultural factors: Migration decisions are often influenced by social ties and cultural factors, such as family obligations, community support networks, and attachment to one's homeland. These factors may outweigh the potential economic gains of moving to an urban area for better job opportunities.

5. Policy and institutional barriers: Many developing countries have policies and institutional barriers that restrict mobility, such as strict immigration laws, lack of access to social services in urban areas, and discrimination against certain groups. These barriers can limit individuals' ability to migrate for economic reasons.

Overall, while income differentials play a significant role in migration decisions, they may not be the sole determinant in the context of the complex institutional and economic framework of today's developing nations. Other factors such as job opportunities, informal economy, cost of living, social ties, and policy barriers should also be considered in understanding migration patterns in these countries.