Critical Releases in Homeland Security: August 12, 2009

"Whether heightened border enforcement reduces future undocumented migration is a question at the heart of most policy debates on U.S. immigration reform. To address this question, most researchers utilize publicly available data on border apprehensions and linewatch hours, which serve as proxies for the flow of unauthorized migration and the underlying enforcement effort, respectively. A standard assumption of most researchers is that apprehensions are a function of linewatch hours. It is conceivable, however, that linewatch hours may also be a function of apprehensions. Although some studies recognize the possibility of a reverse relationship, the implied hypothesis-namely, that apprehensions predict linewatch hours-has not been formally tested. This paper fills the gap by providing a formal time series analysis of the historical relationship between monthly apprehensions and linewatch hours between 1963 and 2004. Overall, the findings indicate that while apprehensions and linewatch hours were strongly correlated in the same time period, past linewatch hours were not strong predictors of future apprehensions, or vice versa. This suggests that, while a strong contemporaneous relationship between linewatch hours and apprehensions exists, the two series may be less useful for forecasting purposes. Although this paper does not assess enforcement effectiveness or deterrence, the preliminary results may assist future researchers by providing empirical justification for econometric specification decisions made when studying border enforcement issues."

"The MedCon:Pre-Event has been designed to estimate the baseline medical care requirements (i.e., the number of persons that would require medical care) of a displaced population following a disaster due to pre-existing medical conditions. Users of MedCon:PreEvent should note that the MedCon:Pre-Event has not been designed for estimating the medical care requirements due to direct impact of the event (e.g., injuries and illness) or additional medical care requirements resulting from the aggravation of the existing medical condition. The intended users of the MedCon:Pre-Event model are public health preparedness planners at local, state, and federal levels involved in addressing the large scale medical care requirements resulting from man-made and natural disasters." Microsoft Excel-based tool and manual available for free download.