Consumer prices (CPI) are a measure of prices paid by consumers for a market basket of consumer goods and services. The yearly (or monthly) growth rates represent the inflation rate. The IPCA-15 (Extended National Consumer Price Index) covers families living in 11 urban areas (Belem, Fortaleza, Recife, Salvador, Belo Horizonte, Rio de Janeiro, Sao Paulo, Curitiba, Porto Alegre, Brasilia and Goiania) with a monthly income of between 1 and 40 times the minimum wage. These consumer price data are collected from the 15th day of the previous month to the 15th of the reference month (e.g. September data are collected from the 15th of August through the 15th of September).