About this website

I am a Senior Lecturer in Economics at University of Sussex. I received my doctorate from University of Oxford. On this website you can find detailed information regarding my scientific research, personal interests, and materials intended for my students.


I thought if you lost the glass you could fit right into one of those Guy Ritchie movies and be smoking with Jason Statham.

One of my students after seeing the picture above.

Working papers

Revealed preference and revealed preference cycles: a survey, with Josh Lanier and John Quah

Summary. A discussion on the importance of different acyclicity conditions in the revealed preference literature. (Invited to the 50th anniversary issue of Journal of Mathematical Economics. This version: April 2024.)


A comprehensive revealed preference approach to approximate utility maximisation

Summary. Nobody believes in utility maximisation. However, we do believe that it is a good approximation of how consumers make their decisions. This paper provides a comprehensive method for eliciting preferences, making out-of-sample predictions and welfare analysis using observable data when the individuals are ‘almost’ utility maximising. (R&R at Journal of Economic Theory. This version: August 2021.)


Eliciting the just-noticeable difference

Summary. According to psychophysics, people are unable to discriminate between alternatives unless they are significantly different. I show how to elicit their preferences from their choices when this happens. This is the semiorder approach. (This version: June 2017.)


Testing for production with complementarities (with John Quah)

Summary. How to tell if the production function at your firm exhibits production complementarities? We develop an axiomatic characterisation of this hypothesis. (This version: September 2014.)


The first draft of anything is shit.

Ernest Hemingway (1899-1961)

Publications

Complete and in chronological order.*

Comparative statics with linear objectives: normal demand, monotone marginal costs, and ranking multi-prior beliefs (2024): Econometrica, 92 (1), pp 167-200, with John Quah.

Summary. Consider an optimisation problem with a linear objective. What is the necessary and sufficient condition under which the set of minimisers increases in a natural sense? We show that it is all about parallelograms. We apply our results to normal demand, monotone marginal costs, and comparative statics in models of ambiguity. Online supplement.


Revealed statistical consumer theory (2024): Economic Theory, 77, pp 823–847, with Roy Allen and John Rehbeck.

Summary. What if individuals care about a distribution of consumption, rather than consumption bundles? We characterise such a behaviour and show that it is equivalent to a model in which the consumer cares only about a statistic of the distribution.


Making sense of the monkey business: Re-examining tests of animal rationality (2022): Journal of Economic Behavior & Organization, 196, pp 220-228, with Roy Allen and John Rehbeck.

Summary. We discuss how to perform revealed preference tests on non-human animals. Spoiler: They do much better than human animals!


Markov distributional equilibrium dynamics in games with complementarities and no aggregate risk (2022): Theoretical Economics, 17, pp 725-762, with Łukasz Balbus, Kevin Reffett, and Łukasz Woźny.

Summary. Nine years in the making, but it’s finally here! If you want to know how to analyse and compute equilibrium transitional dynamics in games/economies with infinitely many agents and private shocks… search no more. This paper contains everything you need.


Just-noticeable difference as a behavioural foundation of the critical cost-efficiency index (2020): Journal of Economic Theory, 188.

Summary. Were you using Afriat’s efficiency index (CCEI) but didn’t know what was its behavioural interpretation? I show that it measures the inability to differentiate between alternatives. Now you know!


A qualitative theory of large games with strategic complementarities (2019): Economic Theory, 67, pp 497–523, with Łukasz Balbus, Kevin Reffett, and Łukasz Woźny.

Summary. We show how to compute equilibria and determine comparative statics in games with a continuum of players and strategic complementarities. Particularly useful when studying interactions in which payoffs of players are affected by the whole distribution of actions, rather than its aggregate.


Revealed time preference (2018): Games & Economic Behavior, 112, pp 67-77.

Summary. How to tell if someone is a discounted utility maximiser? I show how to do it when you observe a finite number of binary choices over delayed rewards. Spoiler: Often anything goes!


Efficiency of competitive equilibria in economies with time-dependent preferences (2015): Journal of Economic Theory, 159, pp 311-325. 

Summary. In exchange economies where preferences of consumers change over time, competitive equilibria are efficient. That’s the result.


Differential information in large games with strategic complementarities (2015), Economic Theory, 59(1), pp 201-243, with Łukasz Balbus, Kevin Reffett, and Łukasz Woźny.

Summary. A follow up to the 2019 paper (although this one was published first). Now you can solve and determine comparative statics in games with a continuum of agents and strategic complementarities, when the information individuals have about the game varies.

* Not necessarily complete nor in chronological order.

Teaching

Teaching materials

All teaching materials are available on Canvas. Find the link below.

Other materials

Wikipedia entry on Monotone comparative statics, prepared with John Quah.


Young man, in mathematics you don’t understand things. You just get used to them.

John von Neumann (1903-1957) in response to Felix T. Smith who had said: “I’m afraid I don’t understand the method of characteristics.”

About me

A short bio

I have been a lecturer in Economics at University of Sussex since September 2018. I received my DPhil in Economics from University of Oxford. My research interests are focused on topics in monotone comparative statics and revealed preference analysis. However, I am also interested in, and have worked on, issues in theory of large games and general equilibrium. You can find my CV below.

Media

My conversation with Kavita Dau – one of my most fascinating and resourceful students. We talk about the reasons I have become an academic, my research, and career. I also give some unsolicited (and questionable) advice to prospective graduate students.

Non-academic interests

I am interested the medieval history of Europe and the Middle East. In particular, I am fascinated with the relations between Byzantine Empire and Kingdoms of Outremer throughout the period of Crusades.

In my spare time, I play the guitar. I adore ragtime, Mississippi Delta blues, and a whole variety of rock-and-roll music that followed. My main inspirations are Son House and Chuck Berry, but I am also a great fan of Johnny Cash… and John Mayer… obviously.

A while ago I have started playing the piano, but my progress is quite disappointing.

As an academic I have the opportunity to travel a lot. I enjoy hiking (usually in cold and remote places) and I am in the midst of obtaining a scuba diving license. Photographs from my travels can be found on my social media. See the link below.

My guilty pleasures include: Dolly Parton, playing the ukulele, Star Trek, and dancing like Kevin Bacon in Footloose (the warehouse scene).


I’m smart enough to know that I’m dumb.

Richard Feynman (1918-1988)

My co-authors

In my career I have been blessed with most extraordinary people who had an immense impact on my personal and professional life. Below I present profiles of those with whom I grew the closest. Fruits of our cooperation can be found in the previous sections. If you would like to learn more about them and their work, feel free to visit their personal websites (links are provided next to their profiles).


Roy Allen (Western University)

Despite being from Ohio, Roy has been officially recognised as one of the best young Economists in Ontario (and there is a great number of fantastic young Economists in Ontario). I met Roy when he joined the statistical consumer theory project I’ve been working on with John Rehbeck. Roy perfectly complemented the group with his ingenious ability to employ econometric methods to the revealed preference analysis. Moreover, his unrelenting enthusiasm and optimism were instrumental in overcoming multiple setbacks that we have experienced during the project. Personally, Roy is a fantastic conversationalist and the best companion for long interstate trips by Grayhound.


*Photo by Kevin Reffett

Łukasz Balbus (Zielona Góra)

Łukasz in one of a kind. He is a fantastic Mathematician specialising in measure theory and infinite dimensional analysis, who is becoming a more and more proficient Economist with every new project. I can not remember how and when we met, but it feels like I have known him my entire life. His technical expertise was absolutely invaluable in our investigation of large games with strategic complementarities, when he was proving the most challenging results on the spot or providing insightful counterexamples with an exceptional ease. Personally, Łukasz is a fantastic colleague who patiently and thoroughly answers every single one of my most basic questions regarding topological spaces and their properties.


John Quah (Johns Hopkins & NUS)

Despite being a Mathematician, John is the best Economist I know. He is an institution. We met in 2011 when I started the graduate program under his supervision at University of Oxford. Without a shadow of a doubt, John is everything one would expect from a supervisor, as he devotes an exorbitant amount of time to his graduate students and eagerly shares his knowledge about the ins and outs of the profession. In the meantime, he successfully pushes the frontier of economic research in the areas of comparative statics and revealed preference theory. Privately, John is a sweet tooth (although he constantly claims to be on a diet) and a great fan of Nigella Lawson’s vocabulary.


John Rehbeck (Ohio State)

John is one of my favourite people on this planet. As an Economist, he is a ridiculously productive researcher and an absolute expert in revealed preference and stochastic choice theory. We have met by a complete accident in 2016 when renting the same AirBnB in Rio De Janeiro. After a few sleepless nights filled with a fair amount of Caipirinhas and dancing in the streets of Ciudad Maravillosa, we have become close friends and partners in crime. John is a great fan of gourmet kitchen who never fails to visit every local Michelin-star restaurant wherever he goes. When the sun sets, you can find him in one of the clubs in Columbus, dancing his worries away.


Kevin Reffett (Arizona State)

Kevin is not an Economist. He is a crusader that quests for a rigorous application of mathematical tools in economic analysis. It is difficult to think of anyone with greater knowledge on recursive methods than Kevin. We have met in 2008 at a game theory conference in Wrocław (Poland) when I was still a carefree undergraduate student. One year later I joined him and the two Łukasz’ to work on large games with strategic complementarities. Kevin is with no doubt the greatest fan of Elvis “the King” Presley I know and apparently a great cook (although I still need to test is myself).


*Photo by Kevin Reffett

Łukasz Woźny (Warsaw School of Economics)

Łukasz is the reason I am an Economist and, hands down, one of the biggest experts in dynamic stochastic game theory. We’ve met when I was a clueless undergraduate student struggling to solve the simplest Bellman equation and hardly passing his Advanced Macroeconomics class. Nevertheless, for some unknown reason, Łukasz thought I would be a good candidate for an academic and helped me immensely with my applications to graduate schools. Many years and three joint papers later I consider him to be a great friend and the best companion for sipping chilled rosé on a hot summer evening in Paris.


He is a mathematical genius.

The sole sentence Richard Duffin wrote in his reference letter for John Nash.

Contact

Email:

p.k.dziewulski@sussex.ac.uk

Address:

Department of Economics
Jubilee Building, Falmer
BN1 9SL, Brighton
United Kingdom