subject to violent conflict, older adults migrate more easily than younger adults; a positive coefficient expresses that, among young adults, those located in conflict-prone communities are more likely to migrate than those not in such communities. The number of reported fatalities from conflict events is sourced from the geo-referenced Armed Conflicts Location Events Data (ACLED). It captures the incidence of violent conflict per year in a 25-kilometer vicinity of each household, and is thus not associated to specific ethnicities but to spatial intensities of violence. This conflict-related variable was interacted with being a young adult to express a lower probability of migration for younger rather than older adults, under the same level of conflict. If we had not controlled for this conflict-age interaction, the level of spatial intensity of violence might also determine the consumption growth of the household, rather than solely through the migration channel.

The fourth excluded instrument is the interaction between the log of the Water Requirement Satisfaction Index (WRSI) for maize and being a young adult at baseline (aged 15 to 24 years), as a proxy measure of a push factor for the migration for young adults. The WRSI for a crop, in a given geographic region and during a growing period or the entire season, represents a function of the water available in the soil relative to the water required by the crop to grow; the lower the rainfall, the heavier the water stress for the crop, and thus, the lower the WRSI (World Bank 2011). This rainfall shock-related variable interacted with being a young adult in 2005/06 expresses a lower probability of migration among those of age to migrate in 2009/10, should the rainfall be high or sufficient to allow for maize crop production. A negative coefficient of this instrument is expected to be associated with migration. In a context of inexistent or weak crop insurance mechanisms, rainfall deficits in origin areas will likely not drive rural migration because it can be expected that the neighboring rural areas, which will be the most likely rural migration destinations, will also face a rainfall deficit. As a consequence, a rainfall deficit would prompt one to leave a rural area in favor of urban migration. While this instrument does determine migration, it does not determine the consumption growth of the household outside the migration channel because poor (respectively rich) households can still be found in high (respectively low) rainfall areas.

Finally, the interaction between the log of the distance to the regional capital and being a young adult at baseline (aged 15 to 24 years) is used as a measure of the increased opportunities for young adults living near the regional capital city when compared with young adults living further away. It can be expected that, among males of age to migrate in 2009/10, an increase in their distance to the regional capital at baseline will be associated with rural rather than urban migration. Distance to the regional capital is used as an excluded instrument since distance to cities generates cost differentials among candidates for migration without directly affecting their consumption paths.

The exclusion variables thus appear in the first-stage regression of the decision to migrate, but not in the second-stage regression specified in Equation (3). As part of goodness-of-fit checks for Equation (3), the relevance of the excluded instruments was assessed through the Cragg-Donald Wald F statistic and Sanderson-Windmeijer multivariate F test of excluded instruments in the first-stage regression, the nonover-identification of restrictions through the Sargan test, and the Hausman test for endogeneity of the migration variable (Baum, Schaffer, and Stillman 2003).

To estimate the effect of moving to an urban destination (defined at the enumeration area level) on consumption growth, Equation (3) is modified into Equation (4) by replacing ���+1, the dummy variable for migration, with ���+1, the dummy variable for migration to urban destinations, taking a value of 1 for 18