Sophie Nottmeyer

Sophie Nottmeyer

PhD Candidate

CEMFI

Welcome!

I am a PhD Candidate in Economics at CEMFI.

My main field of research is development economics, labor economics and spatial economics.

I study how market imperfections affect firms and productivity across locations in low- and middle-income countries, with a particular focus on technology adoption. To answer these questions, I often use geospatial data and combine empirical analysis with structural models.

My projects are supported through funding by STEG, PEDL and The Weiss Fund.

I am on the 2025/26 job market.

My CV is available here.

Upcoming: I will present in the PhD Poster Sessions at the CEPR Paris Symposium (Dec 8, 2025) and the STEG Annual Conference and Theme Workshops 2026 in Nairobi (Jan 10, 2026). Feel free to reach out!

Research

Trac(k)tors of Change: Monitoring, Tractor Mobility and Agricultural Mechanization in Kenya (Job Market Paper)
WB Development Impact Blog
Limited access to mechanization constrains agricultural productivity in developing economies, where rental markets for capital goods remain thin. This paper studies how supply-side monitoring frictions shape the spatial allocation of capital in tractor rental markets in Kenya. I evaluate the introduction of a GPS tracking application that enables tractor owners to monitor operators remotely, combining high-frequency GPS data from around 1,200 tractors and nearly one million georeferenced fields with satellite imagery, an original farmer survey, and a quantitative spatial model. Following adoption, monitored tractors gradually expand their range of operations and reallocate toward areas with higher returns to mechanization, consistent with reduced monitoring costs and improved capital allocation. Remote sensing evidence shows that fields visited by monitored tractors exhibit more effective immediate land preparation and greater sustained vegetation growth than comparable nearby fields, suggesting productivity gains at destination. Model estimates indicate that digital monitoring reduces spatial misallocation by 15% and raises aggregate output by 2%, demonstrating the potential of digital technologies to enhance market efficiency in settings involving the delegated operation of mobile capital.
Advancing Corn Yield Mapping in Kenya Through Transfer Learning
with Ahaan Bohra, Chenchen Ren, Shuo Chen and Yuchi Ma; published in Remote Sensing (2025)
Crop yield mapping is essential for food security and policy making. Recent machine learning (ML) and deep learning (DL) methods have achieved impressive accuracy in crop yield estimation. However, these models require numerous training samples that are scarce in regions with underdeveloped infrastructure. Furthermore, domain shifts between different spatial regions prevent DL models trained in one region from being directly applied to another without domain adaptation. This effect is particularly pronounced between regions with significant climate and environmental variations such as the U.S. and Kenya. To address this issue, we propose using fine-tuning-based transfer learning, which learns general associations between predictors and response variables from the data-abundant source domain and then fine-tunes the model on the data-scarce target domain. We assess the model's performance on estimating corn yields using Kenya (target domain) and the U.S. (source domain). Feature variables, including time-series vegetation indices (VIs) and sequential meteorological variables from both domains, are used to pre-train and fine-tune the deep neural network model. The model is fine-tuned using data from 5 years (2019-2023) and tested using leave-one-year-out cross validation. The fine-tuned DNN achieves an overall R2 of 0.632—higher than both the U.S.-only and Kenya-only baselines—but paired significance tests show no aggregate difference, though a statistically significant gain does occur in 2023 under anomalous heat conditions. These results demonstrate that fine-tuning can reliably transfer learned representations across continents and, under certain climatic scenarios, yield meaningful improvements.
Informality and the City Size Wage Premium: Evidence from Brazil
Cities in middle and low income countries are rapidly urbanizing, generating important economic opportunities and challenges. This paper analyzes how pervasive informality shapes the distribution of productivity gains typically associated with larger cities in Brazil. Using Census data, it shows that informality attenuates the urban wage premium by generating differential returns to density across worker types. Decomposing employment density into formal and informal components, the analysis reveals that formal workers experience strong wage gains from formal density, which are partially offset by a negative effect from informal density, while informal workers only benefit from formal density. These findings suggest that productive advantages of cities are primarily driven by the presence of formal workers, and that informality alters the composition of productivity spillovers in urban labor markets of emerging economies.

Work in Progress

Milky Way: Market Structure and Behavior of Informal Traders in the Kenyan Dairy Sector
with Guanghong Xu and Martin Nandelenga
Ethnic Diversity and Technology Choice in Manufacturing

Teaching

Graduate:

  • Quantitative Spatial Models (TA), CEMFI Summer School (2024)
  • Development Economics (TA), CEMFI (2023, 2024), 4.6/5
  • Urban Economics (TA), CEMFI (2022), 4.6/5

Undergraduate:

  • Big Data: Applications to Spatial Data (Instructor), CEMFI Undergraduate Summer Internship Program (2022)
  • Mathematics for Economists (TA), University of Tübingen (2012)