Lelo Nxumalo

In February 2021, Winter Storm Uri descended on Texas, triggering one of the most catastrophic infrastructure failures in modern American history. Temperatures plunged, demand spiked, and the state’s isolated power grid—operated by ERCOT—collapsed. Millions lost power for days. While utility companies provided their own outage estimates, we can use remote sensing to independently verify the scale of the economic damage. Using Python, Google Earth Engine, and the Difference-in-Differences (DiD) framework, we analyzed the blackout from space. The Natural Experiment: A Tale of Two Grids To measure the true impact of the grid failure, we cannot simply look at Houston in isolation. We need a control group—a city that faced the same freezing temperatures but did not lose power. Enter El Paso . Unlike the rest of Texas, El Paso is not on the ERCOT grid; it is connected to the Western Interconnection. This crea...

In upcoming research, my colleague and I posit that the skill content of a worker’s current occupation is a high dimension piece of information that can function as a job market signal, particularly for low wage, non-post-secondary educated workers. Using the 2013 Skills Towards Employability and Productivity (STEP) Survey data for Ghana, we construct a skill vector for every occupation consisting of a skill measure incorporating routine versus nonroutine; and manual versus cognitive intensity. We then create an occupation relatedness measure across all occupations at the 3-digit ISCO level. The fact that many jobs in different industries share common skills but differ substantially in wages suggests that there may be incomplete information in the labor market and potential pathways for low educated workers to become skilled through alternative routes (STARs). The figure below illustrates the resulting relatedness plot of occupations with node size denoting employment shares and node c...

My colleague and I just had our study published . The study discusses the association between household exposure to negative shocks and social safety net program participation in Ghana. To examine this issue, we link data from high-resolution geospatial maps of drought and flood risks to government administrative data on safety net program beneficiaries at the district level. We find that drought risk is positively associated with household participation in selected, main public social safety net programs. (The corresponding evidence for flood risk is weaker). We interpret the finding to be a result of pre-shock program coverage of drought-prone areas, in part achieved indirectly through the intentional targeting of poor areas by the programs.

I am happy to report that a research paper I have been working on at the World Bank has just been  published . The study takes stock of Ghana's economic transformation by decomposing growth drivers and reviewing labor market changes over time. We use three rounds of nationally-representative household surveys as well as macro-level data to benchmark Ghana with structural and aspirational peers. G hana's post-independence (1957) industrialization strategy focused on large-scale, state-managed manufacturing industries known as import substitution industrialization (ISI). ISI, accompanied by protectionist measures, aimed to develop domestic production and reduce reliance on imports. During the 1960s, Ghana experienced initial success with ISI, witnessing significant growth in the manufacturing sector, which expanded from 2% to 9% of total output by 1969.  However, the protective measures led to excess capacity, and policy reversals in the 1970s caused balance of payments crises....

Below is very preliminary analysis of economic sector linkages in Ghana using the 2015 Social Accounting Matrix (SAM) produced by the Ghana Statistical Service (GSS). I estimate that 17 out of 56 sectors in the SAM have strong backward and forward linkages. These are in the light green part of the figure below.  Backward linkages measure the inter-connections among input suppliers for an economic sector. If a sector increases its output, there will be increased demand from other sectors whose goods and factors of production are used as inputs for the production of the sector. Forward linkages measure the inter-connections among buyers for the output produced by an economic sector. That is, additional output of products is available to be used as inputs by other sectors for their own production and consumption.  In general, agricultural sectors largely fall in the light red part of the plot below signaling low linkages to other sectors. Hover over each dot to see more informa...