Last year, I claimed that you win or lose readers with the introduction of your economics paper. That might have been generous. A lot of people will read no further than the abstract of your paper to decide whether it’s worth reading, sharing, or citing. (Some people may read no further than the title!) So how do you write a compelling abstract?
First, let’s look at empirical work in this area. Dowling and others examined abstracts of papers in Economics Letters and found that abstracts with simpler words and shorter sentences (i.e., more readable abstracts) were associated with more citations later. As Bellemare writes with respect to abstracts, “Do not make the mistake of confusing lack of intelligibility with intellectual rigor.” In a new paper, Dowling and others examine 500+ articles published in The Energy Journal (the journal for energy economics) and find no impact on readability, although they do find that readability has grown dramatically over time. They also don’t find much in terms of length, although comparing abstract length among articles in a single journals can be tricky since most journals have word limits (e.g., 150 words for The Energy Journal) and so variation may be limited. Outside of economics, longer abstracts have more citations in psychology, mathematics, medicine, and physics, but not in sociology. My takeaway from this is to use all the words you’re allowed and use them wisely.
One challenge in economics is that journals vary in how many words you’re allowed: the American Economic Review (AER) and the various American Economic Journals (AEJ) give just 100 words, whereas the Quarterly Journal of Economics (QJE) and the Journal of African Economies give 250. The Journal of Development Economics strikes a middle ground with 150 words. For the AER/AEJ abstracts, authors use their words for about 4-5 sentences. For the longer, QJE abstracts, authors use them for 6-7 sentences.
How should you use those 4-7 sentences? I diagrammed the abstracts of a number of empirical development papers in top economics journals to see if they follow a pattern.
In my introduction advice (adapted from or related to the introduction advice of others), I lay out five main ingredients to the introduction: motivation, research question, empirical approach, detailed results, and value-added relative to the related literature.
Abstracts of development papers in top journals follow a compressed version of this formula. They tend to follow the following structure:
(Often) Start directly with the research question and empirical approach
(Sometimes) Start with one sentence of motivation before jumping into the research question and empirical approach
(Almost always) Spend most of the space on a detailed discussion of the results
(Sometimes) Include one sentence discussing the implications of the results
Below I provide more detail and examples.
Use your first sentence to jump right into the research question and empirical approach (or, less commonly, give a single sentence of motivation)
The most common opening for either longer or shorter abstracts is to jump right into the research question. Papers often incorporate a mention of the design in the same sentence. (And no, they’re not all randomized controlled trials.) Here are examples:
“We study the impact of a personalized technology-aided after-school instruction program in middle-school grades in urban India using a lottery that provided winners with free access to the program.” (Muralidharan et al., 2019, AER)
“I exploit a natural experiment in Indian schools to study how being integrated with poor students affects the social behaviors and academic outcomes of rich students.” (Rao, 2019, AER)
“To show how fast Internet affects employment in Africa, we exploit the gradual arrival of submarine Internet cables on the coast and maps of the terrestrial cable network.” (Hjort and Paulsen, 2019, AER)
“We embed a field experiment in a nationwide recruitment drive for a new healthcare position in Zambia to test whether career benefits attract talent at the expense of prosocial motivation.” (Ashraf et al., 2020, AER)
“We use a randomized controlled trial to study the response of poor households in rural Kenya to unconditional cash transfers from the NGO GiveDirectly.” (Haushofer and Shapiro, 2016, QJE)
The other opening I saw repeatedly is a single sentence of motivation. (I didn’t see any papers with more than one sentence dedicated to motivation.)
“Despite massive investments in teacher professional development (PD) programs in developing countries, there is little evidence on their effectiveness.” (Loyalka et al., 2019, AEJ: Applied)
“Relative-pay concerns have potentially broad labor market implications.” (Breza et al., 2017, QJE)
“The delivery of basic health products and services remains abysmal in many parts of the world where child mortality is high.” (Björkman Nyqvist et al., 2019, AEJ: Applied)
Use most of your abstract to describe your results in detail
On average, the small sample of abstracts I looked at used at least half of their sentences (54 percent) to describe results. Only about half include specific point estimates, but most still go into great detail.
For example, Ashraf et al. (2020, AER)—in their paper on attracting health workers in Zambia—dedicate three of their four sentences to results. First, the main result: “In line with common wisdom, offering career opportunities attracts less prosocial applicants.” (See how they tied it into the literature there?) Second, the heterogeneity: “However, the trade-off exists only at low levels of talent; the marginal applicants in treatment are more talented and equally prosocial.” (Oh ho: the conventional wisdom often doesn’t apply!) Finally, more detail on that result, including an easily citable point estimate: “These are hired, and perform better at every step of the causal chain: they provide more inputs, increase facility utilization, and improve health outcomes including a 25 percent decrease in child malnutrition.”
Romero et al. (2020, AER)—writing about outsourcing education to private schools in Liberia—use the last three of their five sentences to describe results. First, the average results: “After one academic year, students in outsourced schools scored 0.18σ higher in English and mathematics.” Then, heterogeneity in the results: “We do not find heterogeneity in learning gains or enrollment by student characteristics, but there is significant heterogeneity across providers.” Finally, unintended consequences in the results: “Some providers engaged in unforeseen and potentially harmful behavior, complicating any assessment of welfare gains.”
Barrera-Osorio et al. (2019, AEJ: Applied)—writing on alternative cash transfer designs in Colombia—use three of their four sentences for results. First, a result and some interpretation: “Forcing families to save one-third of the transfer increases long-term human capital accumulation by means of additional tertiary education—which is not incentivized—, casting doubt on conditionalities as a driving mechanism.” Second, an additional result: “Directly incentivizing on-time tertiary enrollment does no better than forcing families to save a portion of the transfer.” Finally, some detail on where the results are concentrated: “Whereas forcing families to save increases enrollment in four-year universities, incentivizing tertiary enrollment only increases enrollment in low-quality colleges.”
If you have the space, use a final sentence for the implications of your results
Most of the papers I looked at describe their results right to the end of the abstract. But a subset used a final sentence to lay out what those results mean.
“Our results suggest that unconditional pay increases are unlikely to be an effective policy option for improving the effort and productivity of incumbent employees in public-sector settings.” (De Ree et al., 2018, QJE)
“These findings help inform our understanding of when pay compression is more likely to arise in the labor market.” (Breza et al., 2019, QJE)
“Our results show that (i) the poor are able to take on the work activities of the nonpoor but face barriers to doing so, and, (ii) one-off interventions that remove these barriers lead to sustainable poverty reduction.” (Bandiera et al., 2017, QJE)
Writing a clear abstract isn’t rocket science. But when I looked at a handful of abstracts in lower ranked journals, they were less likely to follow this simple formula, usually by dedicating a couple of sentences to the existing literature. I realize there may be circularity to this: less novel results are published in lower ranked journals and also require more situating within existing literature. But all those AER and QJE papers also exist within literatures. The abstract is the place to sell your results. There is space in the introduction to situate your findings within a broader literature.
I’ll end with a gem from Bellemare’s paper on writing economics papers: “If your title is not repellent, and if your abstract is intelligible to people who are not experts in your field and to people in other disciplines, you have just expanded the scope of your citations tenfold, because whether one likes it or not, a lot of people cite stuff they have only read the abstract of.” True.