Functional forms and the relevance of contiguous migration in the study of migration and employment growth

The authors examine internal migration in the United States and emphasize the importance of decomposing total migration into contiguous and noncontiguous migration flows when analyzing employment change. "In this study, a simultaneous-equation model containing two equations, one for migration and the other for employment growth, has been specified in a general form and estimated by the 2SLS method for total, contiguous and noncontiguous migration flows. Results obtained from the use of 1970 Census data show that noncontiguous migration behaves significantly [differently] from contiguous migration, and that noncontiguous migration, rather than total migration, should be used for the study of factors affecting interstate migration. Results also indicate that the log-linear functional form commonly used in empirical studies cannot be accepted statistically."