Carolina Tojal R. dos Santos

Welcome to my website!

I am a Ph.D. Candidate at the Department of Economics at the University of Michigan

My research fields are Industrial Organization and Environmental Economics. 

I will join the Inter-American Development Bank (IDB) as a research economist.

Here is my CV.



with Bruna Guidetti

Expansion of piped water and sewage collection is a critical issue in developing countries, where public investment is limited. In Brazil, the New Sanitation Regulatory Framework from 2020 intends to stimulate the entry of private providers into the market while setting connection targets: 99% of households with piped water and 90% with piped sewer. We assess the viability of these connection goals under the current regulated prices and compare the distributional impacts of supplemental policies. We use billing data from a major private provider and a structural model encompassing the expansion decisions of the service provider and the connection and consumption choices of consumers. We find that even if the firm expanded water and sewer everywhere, the targets would not be met, with only 43% connecting to piped sewage. Moreover, the expansion is not profitable for the firm. We then simulate charging consumers when piped sewage is available, regardless of connection, and price discounts on the sewer bills. Combinations of these two policies stimulate the firm to expand and consumers to connect, achieving 76% connected to sewer but reducing consumer surplus.

This paper investigates the impact of direct-to-consumer advertising (DTCA) on women’s decisions regarding prescription contraceptives. I use television advertisement data and claims data, applying the Border Approach proposed by Shapiro (2018) to estimate the causal effects of television ads. My findings indicate that a 10% increase in DTCA for short-term contraceptive methods, such as pills, increases demand for the advertised product by 2.7% but also generates positive spillover effects on other branded and generic products within the same category. Conversely, these ads reduce the demand for Long-Acting Reversible contraceptives (LARCs), such as IUDs and implants, leading to a substitution towards short-term methods.

with Ying Fan and Christopher Sullivan

This paper provides a theoretically founded empirical model to simultaneously investigate firm competition and estimate markups. The model nests the standard oligopoly model, but also allows for firm collusion. Different from conduct parameter models, our model is consistent with a series of theoretical models. We show that a nonparametric marginal cost function can be identified, which gives an estimate of markups. Through Monte Carlo simulations, we show that our approach works better in estimating markups than a standard oligopoly model or a conduct parameter model.


Graduate Student Instructor Mentor

Intermediate Microeconomic Theory

Introductory Microeconomics 

Microeconomics - Professional master and undergraduate

Microeconomics and Public Economics