In both 2000 and 2010, two different questionnaires were administered. The short form is administered to the entire Mexican population and collects basic social-demographic information for all household members, as well as characteristics of the dwelling.7 It includes information about the place of residence 5 years prior to the interview (i.e., for 2010, the location of residence in 2005 was asked),8 which permits estimation of the number and basic social-demographic characteristics of the population that returned from the United States in the past 5 years.
A long questionnaire was administered to a random sample of about 10 percent of the total Mexican population in the 2000 and 2010 census. In 2010, more than 2.9 million dwellings were interviewed. Expansion weights9 were estimated for each dwelling based on the sampling weight and on an adjustment factor accounting for differential response rates. The sample provides estimates reflecting the population at the following levels: national, state, state with four community sizes predefined, municipality, and localities with more than 50,000 inhabitants (Instituto Nacional de Estadística y Geografía, 2011b, 2011c).
The long questionnaire includes the questions listed in the short questionnaire, plus a special section on the international migration experiences of household members during the prior 5 years, including those no longer in the household. In addition to the question on place of residence 5 years ago, which allows estimation of return migration between 2005 and 2010, the long questionnaire includes a set of questions on international migration. These questions refer to the migration of any person who is currently living in the dwelling or who lived in the dwelling between 2005 and 2010. Information is collected on the number of people, gender, age at migration, date of last migration, state of residence at the time of the migration, country of destination, country of current residence, date of return (for those who returned), and whether the person is currently living in the same household (Instituto Nacional de Estadística y Geografía, 2011a:36-42). The questionnaire also asks whether the household is currently receiving remittances. The 2010 census sample includes 83,757 households with at
7 The definition of “household” changed between the 2000 and the 2010 Census. In 2000, there could be more than one household per dwelling. In 2010, there was no question about the number of households in a dwelling. This change in the definition needs to be taken into account when comparing the international migration information from the two censuses.
8 This question is asked for all of the dwellers ages 5 years and older.
9 Expansion weights are sampling weights. The word “expansion” is used because it describes the expansion of that sampling unit to the population from which it was sampled.