Mexican Migration Project (MMP)

DESCRIPTION: The MMP is a multidisciplinary research effort between investigators in Mexico and the United States . Each year, during the winter months (when seasonal migrants are home), the Mexican Migration Project randomly samples households in communities located throughout Mexico . After gathering social, demographic, and economic information on the household and its members, interviewers collect basic information on each person's first and last trip to the United States . From household heads, they compile a year-by-year history of U.S. migration and administer a detailed series of questions about the last trip northward, focusing on employment, earnings, and use of U.S. social services. Following completion of the Mexican surveys, interviewers journey to destination areas in the United States to administer identical questionnaires to migrants from the same communities sampled in Mexico who have settled north of the border and no longer return home. These surveys are combined with those conducted in Mexico to generate a representative binational sample.

Two to five Mexican communities are surveyed each year during the months of December and January of successive years. The sample size is generally 200 households unless the community is under 500 residents, in which case a smaller number of households is interviewed. These communities have been chosen to provide a range of different sizes, regions, ethnic compositions, and economic bases. The sample thus includes isolated rural towns, large farming communities, small cities, and very large metropolitan areas. These representative community surveys yield information on where migrants go in the United States , and during the months of July and August interviewers travel to those U.S. destinations to gather non-random samples of 10 to 20 out-migrant households from each community. The U.S.-based samples thus contain migrants who have established their households in the United States .

In April 2004, the Mexican Migration Project publicly released the new MMP93 database. This database contains 93 communities, which includes the original 71 communities plus an additional 22 communities that have never before been available to the public.

CODEBOOKS: The data are divided into core and supplementary files. The codebooks for each file are available on the local area network (T:\Public\Data\MMP). The codebooks do not include frequencies. All three versions of the questionnaire are available online (http://mmp.opr.princeton.edu/databases/ethnosurvey-en.aspx ).

DATA: The data are divided into five core files.

•  The PERS file is a person-level file that provides general demographic information and migration measures for each member of a household, including children not presently living with their parents.

•  The MIG file is a person-level file containing details of all border crossing (up to 25) by each head of household, as well as measures of economic and social activity during the last U.S. visit.

•  The HOUSE file is a household-level file containing information on household composition, economic and migratory activity of household members, land ownership and usage, home/real estate ownership and amenities, vehicle and livestock ownership and financing, and business ownership and operation.

•  The LIFE file is an event-history file detailing the labor and family histories or each head of household, for each year since birth until the year of the survey.

•  The SPOUSE file is an event-history file detailing the labor histories of each spouse of a household head, for each year since birth until the year of the survey.

In addition to these five primary files, there are supplementary files that contain community, national, and MSA-level information. The data are available through the Office of Population Research at Princeton University ( http://opr.princeton.edu/archive/mmp/ ). However, you must first register as a user of the OPR data archive to gain access to the data. The MMP93 dataset is available in both SAS and SPSS format.

WEBLINKS: Additional information about the study is available at the MMP website (http://mmp.opr.princeton.edu/ ).

UPCOMING RELEASES: New news alerts ( http://mmp.opr.princeton.edu/webnews/news-en.aspx) and data alerts ( http://mmp.opr.princeton.edu/databases/alerts-en.aspx ) are posted on the MMP website.