Book review: Humble Pi

Alongside my professional interest in popular economics books, I'm a sucker for popular mathematics books like Jordan Ellenberg's How Not to Be Wrong (which I reviewed here). And I particularly like these books if they are fun. So, I was really looking forward to reading Humble Pi, by Matt Parker.

And I wasn't disappointed. Humble Pi is equal parts sombre (after all, there are plenty of maths errors that have led to tragic outcomes, such as the Challenger space shuttle) and amusing (such as Sun Microsystems employee Steve Null, whose details kept disappearing from their database because his last name was NULL). Parker says that the book:

...is a collection of my favourite mathematical mistakes of all time. Mistakes aren't just amusing... they're revealing.

And he's right. There is a lot to learn from this book, while at the same time being amused by (at least some) of the mistakes. Who knew that there was a word 'frigorific'? (a frigorific mixture is a combination of chemicals that always stabilises to the same temperature). And Parker writes in both an engaging and funny style. Consider this:

Do biologists use Excel to process their data? Is the phosphoglycan C-terminal? Yes! (Well, I think it is. It was that or 'Do BP1FB1 genes secrete in the woods?!' but I wasn't confident about that one either. I'm way beyond my limit of biological knowledge trying to look up even obvious microbiology things.) Look: the point is yes. Cell biologists use Excel a lot.

I laughed, until I stopped. And then I laughed again. And there was lots of that while I read this book. Parker also has some pet peeves that come through in the book, such as a strong aversion to stars shining through the shadowed part of a crescent moon. On that point he even takes aim at the Sesame Street classic, I Don't Want to Live on the Moon.

I'll let him off for the anti-Sesame-Street rant, as the rest of the book is a lot of fun to read. I even found the page numbers starting high and counting down to zero to be quite endearing (actually, if I'm honest, I wish more books numbered their pages that way). If you're looking for a good diversion or a change of pace, and don't mind learning a thing or two about maths along the way, this might be a good book for you. Recommended!

Can a simple email nudge students to seek study help?

Students don't always access the help that they need. Often, it's because they don't realise what support is available to them. I'm interested in any way that we can make it easier for students to access support that enhances their learning and helps them to succeed. So, I was really interested to read this 2020 article by Rita Balaban and Patrick Conway (both University of North Carolina at Chapel Hill), published in the AEA Papers and Proceedings (ungated earlier version here).

Balaban and Conway evaluate the impact of emails (passive nudges) reminding students about two economics support programmes that were available on the UNC Chapel Hill campus. The two programmes were the 'EconAid Center', which provided walk-in peer tutoring during weekdays and early evenings, and a series of five hour-long learning strategy seminars run by the co-authors. Students were randomly assigned to one of two email groups, one of which received weekly reminders about the EconAid Center, while the other received reminders before each learning strategy seminar. The evaluation focuses on the 199 students who consented to participate.

Those emails represent a very light-touch intervention. But did they work? The nudges did get students to engage with the programmes, but only for female students and first-year students, who were more likely to engage with the EconAid Center if they received the email nudges. Female students and students of colour were actually less likely to attend the learning strategy seminars if they received the email nudges. So, at best a mixed result.

Turning to whether the two programmes worked to improve grades:

The coefficients corresponding to the effects of the support programs on performance are positive but insignificantly different from zero.

Now, the small sample of 199 students (and the much smaller samples for subgroups) may simply have been too small to estimate the effects precisely. Participation in the programmes was also relatively low. A larger study might therefore do a better job of telling us whether the programmes actually had an effect or not.

So, file this study away under possibilities for the future. Light-touch nudges may help some students take the first step towards seeking support. A natural extension today would be to test whether similar nudges can steer students towards effective human or AI-assisted study support.

Why the City Rail Link is already showing up in property prices

This past week, my ECONS102 class covered hedonic demand theory, which suggests that when you buy certain goods (like houses, cars, computers, or land), you are really buying a bundle of characteristics, and each of those characteristics individually has value. So, when you buy a house, you are really buying a bundle that includes a number of bedrooms, bathrooms, car parking, views, and access to local amenities. And when those characteristics change, then the value of the house will change.

So, it should be no surprise then that the City Rail Link (CRL) will change property prices, since access to good transport links is a valued characteristic. And buyers are taking notice. The exact opening date of the CRL has not yet been announced, although it has been expected in late August or early September. And yet, in anticipation of higher land values in the future, the demand for land around stations that will benefit from the CRL has increased now. As the National Business Review reported back in June (paywalled):

On the residential front, and after reviewing Real Estate Institute data, CBRE found that while Auckland residential prices have risen 29% since 2016, prices around station catchments – defined as a 10-minute walk (about 800 metres) to catch a train – have climbed by an average 36%.

The top-performing areas were Morningside, Kingsland and Baldwin Avenue in Mt Albert, which came in at 108%, 95% and 84% respectively, despite a similar increase in supply during that time...

If you correctly anticipated that the price of an asset would increase in the near future, and you bought it now, you would reap a 'windfall gain'. However, by buying the asset now, you are increasing demand for that asset. And if lots of others also anticipate higher future prices and decide to buy now, that increased demand (and competition for the asset) will tend to drive prices up now. That theory is consistent with the observed increase in property prices, which the CBRE report notes is concentrated around stations that will benefit from the CRL and not other suburbs.

A combination of anticipatory demand and hedonic demand has pushed up land (and house) prices. Hedonic demand explains why improved transport links are valuable, while the anticipatory demand effect explains why that value can appear before the first CRL train even runs.

This week in research #137

Here's what caught my eye in research over the past week:

• Avina et al. (open access) conduct a meta-analysis of studies into public attitudes toward immigrants in host societies, finding that while preferences are broadly similar across countries and demographic groups, economic considerations have become more influential over time, and evaluations of individual immigrants differ sharply depending on where people stand on the broader immigration debate
• Márquez and Scartascini (open access) evaluated a randomised controlled trial of a behavioural economics course for public officials in Latin America and the Caribbean, finding that the course improves applied reasoning and problem-solving
• De Boer et al. (open access) compare trust behaviour towards AI (ChatGPT 4o) and human receivers using a trust game in an experimental setting, finding no significant differences in trust behaviour either between individuals and groups or between AI and human receivers
• Voorintholt et al. (open access) find that reported climate change worries are on average significantly higher when people are asked whether they 'worry about climate change', compared with when they are asked if they agree that 'climate change 'worries me' (survey wording matters!)
• Morris (open access) challenges whether the concept of 'alcohol use disorder' is confused
• Anagol, Ferreira, and Rexer (with ungated earlier version here) estimate the economic value of zoning reform in São Paulo, finding that the reform increased the aggregate housing stock by 1.6 percent, reduced house prices by 0.4 percent, and produced welfare gains of 0.65 percent of city GDP
• Murphy (with ungated earlier version here) evaluates a randomised control trial in rural Kenya in which selected households received cognitive behavioural therapy and medication to reduce alcohol abuse, finding that the program decreased the likelihood of positive spot breathalyser tests among men by 14 percentage points, the likelihood of heavy drinking by 19 percentage points, and increased household real annual harvest values by 32 percent