The individual prices in the dataset were collected by Banxico for the purpose of computing the Mexican consumer price index (CPI, índice national de precios al consumidor). The information was published by Banxico each month in the official gazette of the Mexican government (Diario Oficial de la Federación). The Diario reports average price quotes for the month.  Most price quotes correspond to the price of a narrowly defined item sold in a specific outlet (for example, corn flour, brand Maseca, bag of 1 kg, sold in outlet no. 1100 in Mexico City).  A number of price quotes pertain to city-wide indexes (for example, the price of tortilla is often an average across all outlets sampled in a market) or, in the case of apparel products, to the price of a small samples of items (typically two to four) belonging to the same outlet and with similar characteristics (for example, they are all men dress shirts).  Observations and their descriptions are the paired index (item, month). The lowest level of  aggregation in the dataset is the product category (generico) level, which is similar to an “entry level item” in the U.S. CPI.  Price histories are referred to as price trajectories.  The period over the price of an item is constant  is a price spell.