El Salvador Connectivity Project Evaluation
The Northern Transnational Highway (NTH) is part of El Salvador’s five-year Compact that was signed in November 2006. The activity is designed to open, improve or rehabilitate approximately 290 km of the NTH. The NTH will provide contiguous and reliable access to communities in the Northern Zone, as well as to main transport corridors, thereby enabling the Northern Zone to participate more fully in the national and regional economy.
The impact assessment will combine propensity score matching (PSM), difference in differences (as it allows controlling for the change in non-observable variables), instrumental variables and regression discontinuity (to control for the remaining potential sources of selection bias) to measure the change in household incomes within the “area of influenceâ€ defined as the area within 30 minutes of access through existing means of communication to the NTH. Additional outcomes that will be evaluated include the reduction of transportation costs and transportation time, an expected increase in land values, access to public services and their impacts on health and education outcomes, changes in labor allocation between farm and non-farm activities, and differentiated gender effects of road improvements.
The evaluation will use household surveys and community surveys. The household survey will interview approximately 5,388 households that are located within 30 minutes of access to the NTH. The questionnaire includes two sections — one that will be answered by a male in the household (including household income and agricultural productivity) and will be interviewed by a male survey taker, and the second which will be answered by a female in the household (including household demographics and expenses) and interviewed by a female survey taker. The separate interviews are intended to get more accurate data on topics that are more familiar to certain people in the household. The community survey includes questions on community infrastructure and access to key markets and social services. The current data collection plan anticipates that each household will be surveyed three times, 1) baseline in November 2008, 2) follow up in November 2010, and 3) final in November 2011. This may change however if there are delays in the construction schedule.