David Colander, 1947-2023

I was saddened this weekend to hear that David Colander, Distinguished Professor Emeritus of Economics at Middlebury College, passed away in the first week of December last year. I didn't know David well, but some ten years ago he and I, along with Mary Hedges, guest edited an issue of New Zealand Economic Papers on innovation in teaching undergraduate economics. We co-wrote the editorial, although David was generous in crediting Mary and I for carrying much of the workload towards the end (if I remember correctly, he was on safari at the time we were writing the editorial).

Aside from co-editing, it was within the broader context of economics teaching that I interacted with David, albeit infrequently. He was Associate Editor of Content for the Journal of Economic Education for a number of years, and alongside being a generous mentor to many authors and students, was the author of an excellent introductory economics text. Although I never assigned that textbook in my classes, I did make use of a number of bits from it. This included, on the first day of teaching my ECONS101 and ECONS102 classes, presenting David's definition of economics (alongside several others). David's definition immediately set his textbook apart from the rest of the field:

Economics is the study of how human beings coordinate their wants and desires, given the decision-making mechanisms, social customs, and political realities of the society.

The focus on embedding economics within a social system was emblematic of how David saw things, at least from my interactions with him. David was also well-known for his contributions to the history of economic thought (an area with which I admittedly don't have great familiarity).

Middlebury College has an excellent obituary, that does much more than I ever could to capture how much David meant to the economics community and his colleagues and students. He will be missed.

This week in research #4

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

• Tillinghast, Mjelde, and Yeritsyan found that class GPAs at the College of Agriculture at Texas A&M University increased by 0.2 points in Spring 2020 because of COVID-19 and then approximately 0.2 points in the subsequent two semesters (open access)
• St Amour presents a life-cycle model of the value of a statistical life year, then derives estimates of various measures of the value of life using data from the US Panel Study of Income Dynamics (see also this post on a related point)
• Gaenssle looks at whether the degree of nudity affects the income of Instagram stars, and finds that it does - for both male and female stars (open access)
• Yamada et al. find that, among female sex workers in Myanmar, higher risk tolerance is associated with a lower transaction price (open access)

New from the Waikato working papers series:

• Tucker and Xu revisit an important 2001 paper in experimental finance on the formation of bubbles in asset markets

Christian missions and HIV in Africa

Spreading Christianity was seen by the colonial powers as a way of civilising the native populations in Africa. Indeed, in 1857 David Livingstone wrote that "neither civilization nor Christianity can be promoted alone. In fact, they are inseparable" (see here). Among the many effects of colonisation, the spread of Christianity is seen as one of the few positive aspects (or, at least, one of the least negative aspects). Christian missions were associated with increased availability of education and (Western) health care. However, this may not have meant that health improved along all dimensions. This 2020 article by Julia Cagé (Sciences Po) and Valeria Rueda (University of Nottingham), published in the Journal of Demographic Economics (ungated earlier version here) presents evidence that historical Christian missions were associated with higher prevalence of HIV.

Cagé and Rueda use data on the locations and characteristics of Protestant missions from 1903 (from the Geography and Atlas of Christian Missions) and data on the locations and characteristics of Catholic missions from 1929 (from the Atlas Hierarchicus), in each case distinguishing between missions with and missions without health facilities. That allows them to compare outcomes for people living closer or further away from historical Christian mission locations with and without health facilities. The key outcome variable is HIV infection status, as recorded in the Demographic and Health Surveys from 2003 to 2013 (which includes over 344,000 individuals across 17 African countries).

In their main analysis, they find that:

...a 10% increase in distance to any mission is associated with a 0.003 unit lower probability of an HIV-positive result... Ceteris paribus, at the median distance to a mission, a 15 km increase in distance decreases the average probability of HIV positivity by approximately 5%.

So, people living closer to historical Christian missions are more likely to be infected with HIV. However, the story doesn't end there, as:

...a 10% increase in the distance to a mission with a health investment is associated with a 0.0005-unit increase in the probability of HIV positivity... This result suggests that, ceteris paribus, at the median distance to a mission that invested in health, a 15 km increase in distance to the health investment increases the average probability of HIV by approximately 0.7% to 1.2%.

So, Christian missions are associated with higher HIV prevalence, but this is offset if the mission had a health facility. The results appear to be somewhat greater for Protestant missions than for Catholic missions. Cagé and Rueda show that their results are robust to various alternatives, including limiting the sample to people living in more urban areas, and the results are similar when using a matching approach (although the sample size is much smaller when relying on the matched sample).

Here's where things get interesting though. The results are not generalisable across all health conditions, as when Cagé and Rueda look at anaemia or stunting, they find that:

...unlike for HIV, proximity to a mission does not statistically significantly correlate with these health outcomes. If anything, we observe improved outcomes (less positive results of anemia or stunted growth), but the relationship is not significant.

So, what is it about HIV that sets the results apart? Cagé and Rueda argue that there are:

...two possible countervailing effects of missions on HIV prevalence. On the one hand, their early investments in health facilities have a positive long-term impact on HIV prevalence, through the persistence of infrastructure and safer sexual behaviors. On the other hand, missionaries left a profound cultural imprint: conversion to Christianity increased the risk of contagion by changing family structures and increased exposure to religious institutions that have struggled to effectively address the epidemic.

Then, they find that sexual behaviours differ markedly for Christians and non-Christians in the DHS sample:

We observe that despite being more educated on average than non-Christians, Christians have riskier sexual behaviors. They have more sexual partners over their lifetime and are more likely to use the services of sex workers. Furthermore, they are also less likely to be abstinent before marriage. Despite being more likely to know that condoms lower the chances of transmitting HIV, they are less likely to know where to find them.

And then, comparing Catholics and Protestants (while noting that the categories are not perfectly separable in the survey), they find that:

Catholics exhibit certain riskier behaviors, like a larger age gap inside the household, or a larger number of sex partners. Protestants are nonetheless more likely to use the services of sex workers over their lifetime, which is a very strong determinant of HIV transmission, and less likely to know that condoms lower the chances of HIV contamination. Although it is statistically significant, the difference is quantitatively very small.

This, combined with the greater success of Protestant conversion in African than Catholic conversion, may explain the larger impact of Protestant missions than Catholic missions in their initial results.

So, it appears that Christian missions have had a long-term impact on health in Africa, and not entirely in a positive way. What can we learn from this? Cagé and Rueda point out that:

...our results may help us reflect on contemporary HIV prevention policies. In the United States, religious conservatives strongly support abstinence-until-marriage (AUM) as the central element of HIV prevention efforts, and this policy periodically receives a large share of the Federal funding... Our long-term perspective suggests that a focus only on “Christianizing” marriage patterns and sexual behaviors is unlikely to be successful.

Indeed. Add this to the evidence base against an abstinence-only approach to the HIV pandemic.

Robert Solow, 1924-2023

I'm a little late to this sad news, but 1987 Nobel Prize winner Robert Solow passed away on 21 December last year. His name will be known to many students of introductory macroeconomics through the Solow-Swan neoclassical growth model, developed independently in the 1950s by Solow and by Trevor Swan. The model is a mainstay of teaching in macroeconomics, and although it has long since been superseded by endogenous growth models, it still provides useful insights for students. Foremost among those insights is that technology (the so-called 'Solow residual' in a growth accounting model) is the driver of economic growth, rather than growth of labour or capital. I also found in my own teaching that students appreciated the model as providing an explanation for why growth rates in low-income countries most often exceed those in high-income countries.

Although I'm a microeconomist at heart, I have a fondness for Robert Solow's work. When I was an honours student, I wrote a long essay for my graduate macroeconomics class on growth theory. That essay received high praise from my lecturer and was a contributor to my decision to pursue a PhD in economics (although ironically, my PhD studies were in applied microeconomics, and I haven't really been involved in macroeconomic research ever since).

On a side note, we remain in a situation where no Nobel Prize winner in economics has celebrated a 100th birthday. Solow passed away aged 99, slightly younger than Maurice Allais was when he died in 2010. The oldest living Nobel Prize winner now is Vernon Smith, who turned 97 on 1 January.

For such an eminent economist, I'm surprised at an apparent lack of memorials across the blogosphere (perhaps the time of year has something to do with it). However, there are good obituaries at the New York Times, Washington Post, MIT News, and Time. As a read-through of those obituaries will tell you, Solow's contributions went beyond his own - he was the thesis advisor for four other Nobel Prize winners (Akerlof, Stiglitz, Diamond, and Nordhaus). Solow clearly made his mark on the discipline of economics. He will be missed.