Economics

Economics: a science of choices

Why does unemployment persist in some regions but not in others? Does raising interest rates really curb inflation? Do digital giants prevent new players from emerging? How can places in childcare or organ transplants be allocated fairly?

Behind these questions lie choices: those made by households, firms and governments. The department's economists seek to understand these choices, measure their effects and inform public decision-making. To do so, they build theoretical models and test them against increasingly rich data: administrative records, surveys, field experiments and digital traces.

The department brings together faculty and researchers from École polytechnique, ENSAE Paris, Télécom Paris and CNRS. All are members of CREST, the Center for Research in Economics and Statistics. This close relationship with statisticians is one of the department's great strengths: methodological rigour lies at the heart of all its research.

Our research areas

The department's work is organised around five main research areas, each with its own seminar where researchers from around the world come to present their work.

Macroeconomics: understanding the economy as a whole

Growth, inflation, unemployment, public debt: macroeconomics studies a country's major economic balances and how they evolve. Researchers in this area analyse how a crisis spreads from one sector to another and how central banks and governments can respond. They also study the role played by the expectations of households and markets. Their work further covers open economies, labour market dynamics and the influence of political institutions on major economic decisions.

Applied microeconomics: measuring the real impact of public policy

Does a support scheme for jobseekers actually work? Does a tax reform reduce inequality? How does an environmental policy affect firms? This area draws on large-scale data and rigorous evaluation methods to answer such questions precisely and independently.

The topics are wide-ranging: employment and the labour market, education, income and gender inequality, the family, health, taxation and social protection, migration, cities, the environment, international trade and development. This is the area that engages most directly with policymakers.

Microeconomic theory: modelling decisions and interactions

How do we make decisions under uncertainty? Why do we cooperate, or fail to? Which voting system best reflects citizens' preferences? How can students be assigned to study programmes in a way that is both fair and efficient?

This area develops the conceptual tools of economics: game theory, decision theory, behavioural economics and collective choice. Researchers also test their hypotheses in the laboratory through experimental economics. Their work has very concrete applications, from school assignment procedures to the design of voting systems.

Industrial organisation: understanding how markets work

How do firms set their prices? Does a merger between two competitors harm consumers? Do digital platforms need specific regulation? Industrial organisation studies competition between firms, the balance of power between producers and retailers, and the effectiveness of the rules that govern markets.

Researchers in this area work on the digital economy and telecommunications, innovation and intellectual property, health and public procurement. Several of them contribute their expertise to competition and regulatory authorities.

Incentives and computation: economics in the age of algorithms

Recommendation algorithms, online ad auctions, cryptocurrencies, AI agents: more and more systems rely both on computation and on strategic behaviour. This new area, at the frontier between economics and computer science, studies how to design such systems so that they remain efficient, fair and robust when everyone is trying to get ahead.

Its topics include market and mechanism design, algorithmic game theory, computational economics, crypto-economics and the incentive issues raised by AI.

Research open to the world

Each year, the five research seminars (Macroeconomics, Applied Micro, Microeconomics, IO and Incentives and Computation) host dozens of international researchers. They are open to faculty, postdoctoral researchers and PhD students from Institut Polytechnique de Paris and beyond. The programme is available on the CREST website. The department also regularly welcomes visiting researchers for stays of several weeks.

Collaborations and projects

Informing public debate. Members of the department are affiliated with the Institut des politiques publiques (IPP), which produces independent analyses of public policy for citizens and policymakers.

Data and artificial intelligence. Researchers take part in the Hi! PARIS centre, dedicated to AI and data science, and in the "Data Science for Economics, Finance and Management" programme run jointly with HEC Paris.

Projects of excellence. Several members of the department lead projects funded by the European Research Council (ERC) and the French National Research Agency (ANR).

Training the economists of tomorrow. Researchers teach at École polytechnique, ENSAE Paris and Télécom Paris. They also run Institut Polytechnique de Paris's Master in Economics and PhD Track in Economics, in partnership with HEC Paris.

Doing a PhD in the department. Every spring, a call for applications is opened to recruit doctoral students on three-year contracts. We encourage applicants to contact their prospective supervisors as early as possible.