Simultaneity bias in migration models: an empirical examination.

A number of migration studies have attempted to explain migration that occurred over a given time interval by means of variables defined for the end of the period and/or variables relating to changes that occurred over the period. Since migration may influence end-of-period levels of explanatory variables by influencing the behavior of these variables over the period of migration, simultaneous-equations bias may be inherent in the parameter estimates of the many single-equation, multiple-regression analyses. This study constitutes an empirical examination of qualitative differences in the parameter estimates of five different types of migration models estimated for two different time periods, 1960 and 1970.