Books

You don’t have the same kinds of information with book sales as you get with academic citations where we can just look at google scholar. The entire industry is a bit of a black box from what I’ve read. Some reports say the median book may sell only around a dozen books. I once heard that the entire book industry is kept afloat by Harry Potter and the Bible.

But I think it’s worth sharing this information because book writing is an opportunity to do creative work that is not the same as what you ordinarily get to do as an academic. In economics, we say that rarely are corner solutions truly optimal. That’s because economists start by assuming a certain listing of preferences that lead them to think utility functions are more likely quasi-concave, and when they are quasi-concave, you get indifference curves in which it’s always preferred to have a little of two things than all of just one.

And I feel that way about books. It’s not that you have to write books or academic articles. Rather, writing books scratches a different itch.

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Trying for best third book on the syllabus

My ambition has always been to be the “best third book on the syllabus”. The first book on the syllabus is the textbook the author uses. These are your Jeff Wooldridge’s. The second book on the syllabus might be if you had assigned both Wooldridge and Mostly Harmless, or maybe a book by Bruce Hansen. Point is, the second book is the paired textbook for the class. And the third book is a large list of supplemental readings. They aren’t obligatory for the students; they just are recommended. And there’s usually quite a few listed.

And my goal has always to be everyone’s third book, showing up on so many supplemental readings so as to try and dominate, not the textbooks (as the Mixtape really isn’t a textbook), but rather to be the book that helps students with the first and second books. No more, no less. Whether I have been successful at that is a different question, but that’s always been my goal.

The new book, Causal Inference: the Remix, comes out some time this year. I turned it in last summer, but I have been slow getting my proofs back. But yesterday, I got the index turned in. I took a knife and slashed through a bunch of stuff, leaving other stuff behind, and just try to trim it down. And with that it’s done.

It’s a weirder book in some ways. I talk a lot about rivers in it, among other things. Rivers are the metaphor I use throughout to help me navigate the different threads of causal inference from the Princeton Industrial Relations Section, the Harvard stats department, the computer science community, the Chicago tradition, econometrics itself. The book is more biographical than the previous one. I am very interested in trying to pin down people in space and time, sociologically, as best I could.

And of course, the causal panel stuff is bloated. I get into the weeds on diff-in-diff, and now it’s two chapters long, instead of one. It’s also sadly going to clock in at around 750 pages. I probably could’ve made two books out of it, but I didn’t, so now there’s one big book. A Big Beautiful Book. We’ll see what people think.

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Mixtape book sales to date and other facts

The 2025 data on the ongoing sales of the Mixtape itself, though, came in this week. It continues to sell . Sales for the English translation is all I have now; it is harder to get China. I’m not sure why. I will probably not have trouble getting the Japanese translation 2025 sales, but at the moment don’t have it.

So what I have done is I’ve asked Claude to do research on book sales, for academic presses and non-academic presses, and then take all the data I have on the Mixtape and make whatever graphics he feels like would fit with this substack (which I copied and pasted to him so he knew what I was writing). But, like I said — I really would like to suggest to economists and other social scientists that they consider book writing. It doesn’t require specializing in them at all. I just personally need to diversify my creative writing across different domains, including academic writing but not exclusively, as otherwise I’ll burst.

One of the more interesting developments though was that the audio rights were sold to a company called Tantor Media. I’m sure that listening to someone explain matching estimators and two-way fixed effects will be riveting.

But here are some facts that Claude Code came up with visually presented. Here’s cumulative sales so far across all three translations: English, China, Japan.

I asked Claude Code to then do research on where it fits in the distribution of books. It looks like it’s basically putting it on log scale. Not sure about these data sources, but I had /referee2 and my new skill /fletcher both do a critique and then get a rewrite. Not quite a bestseller threshold, but somewhere up there.

Here it is year by year. Apologies that the labels suck. I usually work harder to get these straightened out. But you can see 2023 was big because of China translation. But the English has stabilized. The 2025 numbers were just a hundred less than the 2024 numbers for US / English speaking.

And then here is that same thing over time. You can see the English speaking trajectory separately.

So that’s been quite a fun experience to be honest. And thanks everyone for your encouragement and support for me personally and professionally all these years. It’s buoyed my spirits.

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What comes next?

So, on the book, front, what comes next after the Remix? Not sure. I have been toying over the years with different projects. At different times, these have been the ideas I’ve toyed with, some I went further on than others.

1. A biography of the Nobel Laureates — David Card, Guido Imbens, Josh Angrist

2. A biographical history of the Princeton Industrial Relations Section that would encompass the Nobel Laureate stories.

3. A biography of specific labor economists — specifically Josh Angrist, David Card, Francine Blau have all been people I’ve thought about.

4. A book on probability based on my current Harvard class, Gov 2001, with again the goal to be the “best third book on the syllabus”.

5. A book on “AI Agents for Research Workers”. This one I have done the most work on, as it would be largely inspired by the 38 or so substack posts here, as well as the different public talks I’ve given about generative AI over the years, as well as the class I developed at Baylor, “The Economics of AI”. It would mix my personal style with an effort to helping people ramp up while thinking about the larger implications of AI on work.

6. And perhaps my weirdest idea — a series of books aimed at high school and early college age kids involving a private eye named Jack Stone who solves usually murders that happen at universities. They unfortunately require he learns what diff-in-diff and instrumental variables is so that he can figure out clues. It sounds great on paper — or maybe it sounds bad on paper — but I did tons of research on it two years ago one summer when I was supposed to be working on The Remix. I have a very vivid dream sequence in one chapter of Jack Stone meeting with Alberto Abadie floating together over the Charles River and Alberto explaining kappa weighting and instrumental variables to the Jack. That was a wild idea I had. I was basing it on various genre tropes, notably Raymond Chandler formulas, and so in Europe was reading as many of those books as I could to try and figure out just what made a Chandler plot a Chandler plot. Guess what doesn’t make a Chandler plot a Chandler plot — characters explaining IV to the private eye.

So who knows. I am going to Europe for 9 weeks starting early May. I’ll do this:

• Zurich

• Glasgow

• Third Annual CodeChella Madrid

• European Commission in Milan

• Conference talks in Pisa

• Berlin

• Short break

• Maastricht

• San Sebastián for a vacation

And then I come back to Boston. My lease here runs out the end of August. I am currently debating whether to keep it for a year and commuting back and forth or whether to just let it go. There’s personal reasons for it, and I keep weighing pros and cons. I have another month to decide, so wish me luck in deciding it.