Tuesday, 21 July 2026

Farmers can't avoid high synthetic nitrogen fertiliser prices by switching to organic fertiliser

The New Zealand Herald reported yesterday:

New Zealand farmers face hefty increases in the price of fertiliser this spring as a result of the escalating US-Iran conflict and the war in Ukraine.

The Middle East plays a big role in the global fertiliser market because of its supply of natural gas and mineral resources.

Russia is also a major supplier of fertiliser.

Renewed hostilities in the Persian Gulf – and the virtual closure of the Strait of Hormuz – have driven oil prices up to about US$90 ($154) a barrel for Brent crude, the international benchmark.

Synthetic nitrogen fertiliser is generally manufactured from ammonia created using the Haber-Bosch process. This requires hydrogen, which is often derived from natural gas (mainly methane). Since the Middle East is a major supplier of natural gas, a lot of nitrogen fertiliser is manufactured in the Middle East. The current conflict in the Middle East is constraining the transport of nitrogen fertiliser from the Persian Gulf, reducing the supply of nitrogen fertiliser.

The effect of this on the market for nitrogen fertiliser is shown in the diagram below. The market was initially in equilibrium, where demand D0 meets supply S0, with a price of P0 and a quantity of nitrogen fertiliser traded of Q0. The Middle East conflict reduces shipping of nitrogen fertiliser, which decreases supply to S1. This increases the equilibrium price of nitrogen fertiliser to P1, and reduces the quantity of nitrogen fertiliser traded to Q1.

Can farmers avoid the higher price of nitrogen fertiliser by switching to an alternative product, such as organic fertiliser (compost, or manure)? Not really. Consider what happens in the market for organic fertiliser, shown in the diagram below. Before the change in the price of nitrogen fertiliser, the market for organic fertiliser was in equilibrium, where demand DA meets supply SA. The equilibrium price was PA, and the quantity of organic fertiliser traded was QA. Since nitrogen fertiliser and organic fertiliser are substitutes, and nitrogen fertiliser is now relatively more expensive (as shown above), farmers switch to the relatively cheaper organic fertiliser. That increases the demand for organic fertiliser from DA to DB, increasing the equilibrium price of organic fertiliser from PA to PB, and increasing the quantity of organic fertiliser traded from QA to QB.

So, the effect overall is that the price of both nitrogen fertiliser and organic fertiliser increase. Farmers cannot easily avoid high fertiliser prices. We can expect that to flow through into higher prices for farm produce, as well as lower profits for farmers.

Monday, 20 July 2026

How career stereotypes shape students' choice of major

What jobs do accounting majors get? How about psychology majors? Or economics majors? If you answered, respectively, 'accountant', 'psychologist', and 'economist', you're probably far from alone. When most people think about particular fields of study, they have stereotypical jobs in mind, and they're far more likely to believe that majors get the stereotypical job than any other job. Even in the case of economics, where very few graduates will go into a job with the title 'economist' (many will go into a job with some sort of 'analyst' title, like a business analyst, market analyst, or financial analyst, etc.).

A new article by John Conlon (Ohio State University) and Dev Patel (Brown University), published in the Quarterly Journal of Economics (open access) demonstrates the extent of this stereotyping. They also show using a simple survey experiment that students' stereotypical views can be changed, affecting their choice of major.

The first part of the paper compares students’ beliefs about the careers associated with different majors with actual major-career combinations in the 2017-2019 American Community Survey. Conlon and Patel then use the CIRP Freshman Survey, covering more than nine million first-year students between 1976 and 2015, to compare students’ expected careers with the occupations subsequently observed among graduates from the same cohorts. In that, they find:

...large, systematic, and persistent differences between the careers that freshmen expect to attain and the actual occupations they go on to have... We see that twice as many students expect to become artists, counselors, and lawyers (about 5% each) than actually do (2%–3% each). Four times as many students expect to become writers and doctors (2.7% and 11.1%) than do (0.7% and 2.8%).

Interestingly, the occupations that students most overestimate themselves as having are those that are rare and representative of particular majors (like writers or artists), while those that are most underestimated are those that are common alternative occupations that many majors may later hold (like teaching or business). Conlon and Patel also show using implicit association tests that people:

...strongly and systematically associate majors with their representative careers: implicit associations are 0.30–0.36 standard deviations higher for representative major–career pairs than for nonrepresentative pairs...

This supports Conlon and Patel’s interpretation that stereotyping contributes to students’ exaggerated beliefs about the connection between majors and the corresponding representative careers. Conlon and Patel then show using a theoretical model that stereotyping can increase misallocation of labour. What that means is that, given the occupation in which a graduate eventually works, that person might have been better off studying a different field. They also present suggestive evidence that links greater stereotyping with job dissatisfaction and regrets about the chosen field of study.

The welfare loss, job dissatisfaction, and regret, then motivated a survey experiment where Conlon and Patel attempt to correct for the stereotyping. The survey experiment proceeded as follows, using students from Ohio State University:

The survey began by asking students the percent chance that they would graduate with the two majors they selected as being most likely to pursue (their “top-ranked” and “second-ranked” majors). It then asked their self and population beliefs about the likelihood of each career group conditional on these two majors. Students were randomly sorted into a control group and a treatment group. Those in the control arm answered questions about their classes so far that semester and how they had (or had not) contributed to their major and career plans...

In the treatment arm, information modules provided students with the actual distribution of careers conditional on each of their top two majors according to data from the [American Community Survey]. For each major, it told them several headline numbers about the frequency of the careers they had listed as their most likely jobs if they graduated with that major...

Conlon and Patel then looked at whether assigning a student to the treatment group, where they received accurate information about the chance their top-ranked majors would lead to particular careers, affected students' beliefs about their own chances of working in each major's 'representative career'. They found that the information partially (but not fully) corrects students' misbeliefs about the chance of attaining the representative career, and that:

...reducing students’ self beliefs about their chance of having their top-ranked major’s representative job by 10 percentage points decreases intentions toward that major by 0.11 standard deviations (about 3.5 percentage points, p < .05).

So, when accurate information lowers students' beliefs about their chances of obtaining the representative career associated with their top-ranked major, their intentions towards that major, and their enrolment in that major, decline. Interestingly though, correcting beliefs about a student’s second-ranked major can make that alternative more attractive. The response therefore depends on both the information that students receive and how much they value the different careers.

That would seem to be good news for some university majors, where the 'representative occupations' are relatively common (e.g. accounting or marketing) and bad news for other majors where the 'representative occupations' are less common (e.g. journalism or film studies).

Where does economics fit in as a major? Sadly, Conlon and Patel don't answer that question, as they combine economics with accounting, finance, marketing, and other business fields. In that broad group, 73 percent of prospective majors expected to enter a business career, compared with 47 percent of graduates who actually did so. So economics may not escape stereotyping. It may simply be stereotyped as a route into 'business', rather than more narrowly as a route to a job called 'economist'. However, we don't know for sure from these results.

Would better information help prospective economics students to make better choices? On the one hand, it might deter students who see economics as a guaranteed path to one particular career, but it might attract others by showing that economics is not tied to a single occupation. Perhaps the problem for economics is not a lack of possible career destinations, but that its many potential destinations are less vivid than the single job title of 'economist'.

[HT: Marginal Revolution, back in 2022 when it was Conlon's job market paper]

Saturday, 18 July 2026

Will generative AI mean the end of rational ignorance?

In this Substack post back in March, Andy Hall made the case for generative AI to create 'political superintelligence':

The more I work with and study AI, the more I believe it can give every human being on the planet access to a sort of political superintelligence, if we shape it right. And that intelligence, in turn, can make governments smarter and more effective, representatives more faithful, and institutions more responsive than anything we’ve built in over 2,000 years of experimenting with democracy.

Hall's post is worth reading in its entirety, but I want to explore a related point - will generative AI mean the end of rational ignorance for voters? Rational ignorance is the idea that it may be better for voters to not know what decisions policymakers are making on their behalf. That's because it's costly (in terms of time and effort) for voters to keep track of how the decisions that policymakers (and politicians) make on their behalf will affect them (economists call those monitoring costs). The benefit that a voter would receive by becoming informed of what policymakers (and politicians) are doing is relatively small, because their ability to change an election (and therefore policy) is very small. When the monitoring costs are greater than the benefits of being better informed, then voters would be better off not paying the monitoring costs. That is, voters would be better off not paying attention to what the policymakers (and politicians) are doing - the voters would be better off remaining rationally ignorant. This theory of rational ignorance was introduced in the 1950s by the late economist Anthony Downs.

Where does generative AI fit into this? Generative AI could meaningfully lower the monitoring costs for voters, as it gives the opportunity for voters to ask for quick summaries of policy proposals that may affect them. This will be even more effective as generative AI understands more about users' preferences. Moreover, agentic AI offers voters even greater opportunity to investigate what policymakers (and politicians) are doing, at relatively low cost.

When the monitoring costs decrease, then the rationale for voters to remain rationally ignorant weakens. We might expect voters to become more engaged with what the government is doing on their behalf, and to be more active in engaging with government to make their preferences known. Or, at least, maybe voters will delegate these activities to their favourite agentic AI model.

There are, of course, some reasons for caution. Generative AI might reduce the cost of obtaining political information without reducing the cost of checking whether that information is accurate or unbiased. Moreover, an overly sycophantic generative AI that knows the voter's preferences might reinforce the voter's existing views rather than challenging them. So, perhaps generative AI simply moves the monitoring costs from monitoring the government to monitoring the generative AI?

Hall makes the point that political superintelligence has the potential to increase the quality of governance. If generative AI enables voters to become better informed at low cost, it could strengthen political accountability. Policymakers (and politicians) who know that voters can easily scrutinise their decisions may be less willing to act against voters’ interests, or may face greater consequences when they do.

We may not have political superintelligence yet, and large numbers of voters may still be rationally ignorant. However, it may not be long before we start to see some substantive changes in the political process, driven in part by the emergence of generative AI.

[HT: Marginal Revolution for the Andy Hall post]

Friday, 17 July 2026

This week in research #135

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

  • Katz and Jung (open access) estimate the macroeconomic impact of generative AI using cross-country data over the period 2022 to 2025, finding that generative AI contributed to increasing the productivity of most workers, regardless of their education, contract type, full or partial work time, and vulnerability level
  • Dills and Raghav (with ungated earlier version here) find that state legalization of recreational marijuana in the US substantially reduced arrests and disciplinary incidents for drug law violations on college and university campuses
  • Wang and Wong find an overall negative association between financial literacy and use of Buy-Now-Pay-Later services in the US
  • Funahashi and Cardazzi (with ungated earlier version here) find that sports stadiums increase the value of nearby properties in Japan
  • Sayre (with ungated earlier version here) finds no evidence that Airbnb entry leads to a substantial increase in eviction filings overall, but that there is a modest increase in eviction filings in neighbourhoods with a high poverty rate and/or a high concentration of renter households
  • Hampole, Truffa, and Wong (with ungated earlier version here) find that female MBAs are 24 percent less likely than male MBAs to enter senior management within 15 years of graduation, and that having a larger proportion of female MBA section peers increases the likelihood of entering senior management for women but not for men