Data and Methodology

 

Data and Methodology

Net internal migration rates are obtained at the district level from the latest the Republic of Yemen census implemented in 2004. The census has information on2,752,629 households with 19,708,760 individuals living in 333 districts. It provides information on the current residence, previous residence and place of birth of all individuals living in the Republic of Yemen at the time of the census.Information is also available on the number of years each individual has been living in the current residence, which along with age enables us to compute net internal migration rates for different age cohorts. For each cohort, we have 333observations corresponding to the 333 districts in the Republic of Yemen (as of the administrative structure in 2004). Considering seven cohorts corresponding to age groups defined at five years of interval for the population aged 20–54, this provides us with 2,331 observations. The census also provides demographic and socioeconomic information including the level of education of the population, its occupation and employment characteristics, and the extent of urbanization. Finally, we also have at our disposal poverty estimates at the district level that were obtained through the combination of household and survey data through the poverty mapping technique (see Elbers et al. 2003).In addition, information on the distance between major cities in each districts calculated from the highest population center in each district to all other districts using an Euclidean distance function in ESRI ArcGIS 9.3 software, and the same procedure is used for distance to the coast. Travel time to the nearest city with 100,000 populations uses a methodology developed from Nelson (2008)with regionally specific information (World Bank 2011). The road data providers of asphalt roads. The mean slope of district land is derived from global dataset by Verdin et al. (2007). The percentage of irrigated land is taken from Global Map of Irrigated Areas version 4 (Siebert et al. 2005; Siebert,Hoogeveen, and Frenken 2006). Weather data on annual mean temperature and rainfall and their variability are collected from BIOCLIM (Busby 1991).Denoting by Yi the net internal migration rate to district to as a proportion of the population of the district, and by Xi the characteristics of the district, we estimate a standard regression using a fractional logit model