El Salvador, Honduras and Mexico (2010). Among those most frequently cited in available studies are slower growth of the demand for less-skilled labour, a slight decrease in the impact of technical change on the demand for higher-skilled workers, an increase in formal wage jobs and the impact of labour and income policies implemented in some countries. The strata have w'ell-differentiated profiles according to the variables associated with individuals, be they personal attributes or other factors linked to their insertion in the production system. One of the more typical findings of distribution analyses is that education level is the one variable that explains most of the variation in income level between individuals.