The authors (one of them, Enrique Dussel Peters, is a former graduate student) of the latest Monitor of Mexican Manufacturing (pdf) have come up with an ingenious device for measuring the purchasing power of the minimum wage in that country: the Tortillímetro.
What they find, for example, is that, while the minimum daily national salary would have been enough to purchase 32 kilos of tortillas in 1984, by October 2012 it had fallen in real terms to a level sufficient to purchase only 5 kilos of tortillas.*
According to the authors, tortillas are the second most important item in the Mexican basic consumption basket, after beef. The poorest 10 percent of the Mexican population spends approximately 10 percent of its total expenditures on food and drink on tortillas.
*According to official statistics (in a private communication from one of the authors), 24.6 percent of the Mexican labor force receives the minimum daily salary, while 76.1 percent receives three minimum daily wages or less.