Migration, Trade Unions, and the Informal Sector: A Note on Calvo
扩展了卡尔沃模型，区分城市正规与非正规部门，引入基于预期效用差异的迁移决策和工会的功利主义目标函数，发现政府通过正确政策可实现最优，与卡尔沃结论相反。
tends to be very sticky, a feature which renders some of the standard policies for reducing urban unemployment (or underemployment) totally ineffective. In particular, it is observed that in the Calvo model, a first-best optimum cannot be obtained without the imposition of some migration barriers. In this note, we attempt to generalize the Calvo model by incorporating the following new features. First, we distinguish between the two components of the urban sector the modern formal part and the traditional informal part. Secondly, the individuals are assumed to migrate from the rural to the urban sector in response to a differential in expected utility rather than in expectedincome, thereby highlighting the role of risk-aversion in individual migration decisions. Finally, following the new literature on trade union behavior,2 the present model posits a utilitarian objective function for the trade union, a formulation which is considered an improvement over the one put forward by Calvo. An important conclusion of the present exercise, which sharply contrasts Calvo's conclusion, is that the government, by setting its policies correctly, can achieve a first-best optimum for the economy. This difference in result is due obviously to the differences in specification, in particular, of the objective function of the trade union.