Transition to Daylight Saving Time and student academic performance

The transition to Daylight Saving Time (DST) caught me out this weekend. Fortunately, I don't feel like I lost sleep as I was already exhausted from teaching this trimester. Putting aside teacher performance, the idea that losing an hour's sleep, or disruptions to the body's natural circadian rhythm, affects students' academic performance is a common working hypothesis in education circles. So, I was interested a couple of weeks ago to read this 2017 article by Stefanie Herber, Johanna Sophie Quis, and Guido Heineck (all University of Bamburg, in Germany), published in the journal Economics of Education Review (ungated earlier version here).

They used data from 22,000 European fourth-grade students from six countries, drawn from the 2011 waves of the Trends in International Mathematics and Science Study (TIMSS) and Progress in International Reading Literacy Study (PIRLS) studies (see here for more on those studies). The interesting thing about the 2011 waves is that, in the countries that Herber et al. look at, they know on what date the students were assessed, and they can identify some students who were assessed just before a change into DST, and other students who were assessed just after the change into DST. Since schools were effectively randomly assigned to when their students were assessed, this provides a useful quasi-experiment of the effect of DST on student academic performance.

Herber et al. looked at how maths, reading, and science performance differed by DST status for these students, and found that:

...students scored about 4 points lower in both math and science when tested during the week after the clock change. Given a standard deviation of about 72 and 70 points, respectively, test scores in the week after the clock change drop by roughly 6% of a standard deviation. These effects are not substantial in terms of either statistical significance or magnitude.

That quote doesn't make it particularly clear, but the effects were both tiny and statistically insignificant. In other words, DST made no difference to how well students performed on these low-stakes tests in maths, reading, or science. Herber et al. also looked at the effects on performance for eighth-graders, and again found effects that weren't consistently statistically significant and were small in magnitude (albeit on a smaller sample of countries). They conclude that:

This might be due to the fact that one hour of sleep loss is not enough to unbalance circadian clocks to the degree that performance within the following week measurably declines...

Based on our research, it is fair to say that neither parents, nor children, nor competence testing agencies (or even policy makers) have reason to worry about the alleged harmful effects of the clock change on low-stakes test performance.

So, we should probably stop worrying (if we ever were) about the effect of Daylight Saving Time on student academic performance.

Is there an acne premium as well as a beauty premium in labour markets?

I've written a number of times about the beauty premium in the labour market (see here and here, as well as here for my review of Daniel Hamermesh's excellent book Beauty Pays). More attractive people earn more. Hamermesh notes a number of potential mechanisms that might underlie the beauty premium.

However, in an interesting twist, a 2019 article by Hugo Mialon of Emory University (whose previous work includes the economics of faking orgasms) and Erik Nesson (Ball State University) looks at whether there is a premium associated with having acne in high school. They use data from over 43,000 adolescents in the Add Health survey, and find that:

...having acne in high school is positively associated with overall grade point average (GPA), mathematics GPA, and science GPA in high school; positively associated with earning an A in high school math, science, history/social studies, and English; and positively associated with completing a bachelor’s degree. The associations are generally stronger for women than for men... We also find some weak evidence that acne is associated with higher future personal labor market earnings for women.

Mialon and Nesson try to argue that acne is exogenous, meaning not related to any variable that in turn is related to student academic outcomes or later earnings. They show that having acne is:

...not related to measures of socioeconomic status, including parental education levels or most measures of family structure.

I don't find those particular results convincing. Parental education is likely to be measured with error (particularly since the data are drawn from the adolescents, not from the parents), and Mialon and Nesson include "don't know" and "missing" as categories in their education variable, which isn't a particularly robust way of handling it. So, I don't think we can interpret these results as necessarily causal, even though Mialon and Nesson provide some evidence of a plausible mechanism:

In theory, having acne may reduce feelings of being socially accepted, thereby reducing time spent socializing and increasing time spent studying, which may be conducive to educational attainment.We find strong evidence that having acne is associated with feeling less socially accepted and less attractive. Interestingly, we also find that acne is associated with reduced participation in sports clubs and increased participation in nonsports clubs, suggesting a possible shift from physical to intellectual pursuits.

Perhaps that explanation is true. Or perhaps adolescents whose parents had acne, and whose parents also achieved better in school, spend more time on academic pursuits. Is the causality occurring in this generation, or the previous generation? Or the one before that? It's an interesting question, but this should be far from the last word on this topic.

[HT: Marginal Revolution, last year]

Read more:

• Blonds have more fun (or rather, they get paid more)
• The beauty premium in undergraduate study is small, and more attractive women major in economics
• The beauty premium in the LPGA
• The beauty and height premiums in the labour market

The optimal amount of screen time for kids

At the start of the year, Cyril Morong (The Dangerous Economist) had a post titled "Are kids getting "too much" screen time?":

Kids might be spending alot [sic] of time on their phones, computers tablets, etc. watching videos, texting, etc. But is it too much?

A person can do too much (or too little) of anything. The optimal amount is found where marginal cost (MC) equals marginal benefit (MB). It is a good idea to keep doing something if the MB of the next unit is greater than the MC. In fact, you keep doing it right up to where they are equal (there is a graph below to illustrate this).

I want to pick up where Cyril left off, because there's some key points missing from his explanation. Anyway, the relevant diagram is laid out below. Marginal benefit (MB) is the additional benefit of one additional hour of screen time. In the diagram, the marginal benefit of screen time is downward sloping - the more screen time a kid gets, the less additional benefit another hour provides. The first hours of screen time each day are cool and exciting (maybe?), but once you've watched some the cool factor starts to wear off. Even kids get satiated (they call it 'bored'). Marginal cost (MC) is the additional cost of one additional hour of screen time. The marginal cost of screen time is upward sloping - the more screen time the kid engages in, the higher the opportunity costs (they have to give up more valuable alternative activities they could be engaging in, like homework, or sleep). The 'optimal quantity' of screen time (from the perspective of the kid) occurs where MB meets MC, at Q* hours of screen time. If the kid watches more than Q* hours (e.g. at Q2), then the extra benefit (MB) is less than the extra cost (MC), making them worse off. If the kid watches less than Q* hours (e.g. at Q1), then the extra benefit (MB) is more than the extra cost (MC), so one more hour of screen time would make them better off.

So there is an optimal amount of screen time for kids and, unless the benefit of the very first hour is less than the cost, the optimal amount of screen time is not zero. But it's probably not all-day-every-day either.

Wading through sludge

In Saturday's book review post for Sendhil Mullainathan and Eldar Shafir's book Scarcity, I noted that the book fell a little bit short in terms of the linkages with behavioural economics. That was further highlighted to me when reading this new article by Cass Sunstein (co-author with Richard Thaler of the book Nudge), published in the journal Behavioural Public Policy. Sunstein highlights the role of 'sludge', which he defines as:

...‘a viscous mixture’, in the form of excessive or unjustified frictions that make it difficult for consumers, employees, employers, students, patients, clients, small businesses and many others to get what they want or to do as they wish...

When a student seeking financial aid has to fill out an elaborate application form with dozens of difficult questions, that is sludge. When a firm requires a consumer to call to cancel a subscription, and keeps them waiting on hold for a long time before they can deal with a customer service representative, that is sludge. When a potential immigrant has to jump through multiple hurdles, filling out endless paperwork and providing copious amounts of information, a lot of that is sludge. Dealing with sludge is frustrating, disheartening, and demotivating. It can easily lead the student to give up on applying for financial aid, the consumer to give up on cancelling their subscription, or the potential immigrant giving up on their dreams of immigration.

Sometimes the creation of sludge is inadvertent, but often it is intentional. You can imagine that the example of the difficulties in cancelling a subscription may well involve an intentional action on the part of the firm. At the very least, they won't be looking to make it easier to cancel a subscription.

Reducing sludge should be an important goal. As Sunstein notes:

Simplification and burden reduction do not merely reduce frustration; they can change people’s lives... An underlying reason for this is that our cognitive resources are limited...

It is at this point that the link to scarcity is apparent. Sunstein, to his credit, does reference Mullainathan and Shafir on this point. When people are dealing with limited cognitive resources - when they are facing extreme scarcity - burdening them with sludge is simply going to exacerbate their problems. Think about all the times where we burden the poor with excessive paperwork or require costly or time-consuming in-person appointments with case managers at Work and Income or StudyLink - applying for welfare benefits, food grants, student loans, etc. Is all of this necessary, or is the government simply putting obstacles in the way and preventing the people who need assistance from obtaining the assistance that they need? Sunstein argues for what he terms 'sludge audits'. It's an idea worth thinking about.

Sunstein's article makes some important points, and should be required reading for public policy students and for those working in the government sector.

[HT: Marginal Revolution, last year]