I reviewed a paper on Special Economic Zones in Vietnam, published in the Journal of Development Economics (2025).
The paper looks at how Special Economic Zones and Foreign Direct Investment affect the labor market in Vietnam. Using difference-in-differences, the authors find that expanding Special Economic Zones led to workers moving from unpaid agricultural work to receiving wages at firms. The effects were stronger for women, and workers experienced higher earnings and better quality of employment.
The research design is solid. Difference-in-differences lets them compare areas that received Special Economic Zones to areas that didn't, which controls for differences that don't change over time and general trends happening everywhere. The data sources are detailed and creative. They used old satellite images from Google Earth to measure how much land was built up inside the zones over time, and combined that with individual data from national surveys between 2009 and 2019 to study changes in employment, gender, education, and location. They focused on a time period when Vietnam was becoming more connected to the global market, and only included areas that received zones after 2009, comparing them to areas that planned to get them later. That helps control for non-parallel trends.
One thing I'd question is that although they say the districts were similar before treatment, they could show more proof with tests or graphs. They also briefly mention accounting for migration, but I think that needs more attention since the labor market effects could partly be driven by new workers moving in.
I'd also want to see them explore whether different types of zones (manufacturing vs. service) affect workers differently. And they could expand by looking at how housing prices and services around the zones are affected, which would give a fuller picture of the impact.