Informal employment is not exclusive to low-productivity sectors, where 70.5% of wage workers have no formal contract, for 30.8% of wage workers in medium- and high-productivity sectors are also in that position. Moreover, 63.7% of male wage workers have formal contracts compared with 61.8% of women, although a slightly lower proportion of men have long-term contracts (see table II. Its variations are linked to the behaviour of human capital and patterns of productivity, the competitiveness of the sectors providing the employment, and the level of protection and negotiating power of workers, which in turn is related to factors such as the degree of unionization and the possibility of collective bargaining.