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Problem definition: Vaccination campaigns often face significant operational challenges such as limited stockpiles, vaccine delivery delays, and constrained administration capacity. In such contexts fractional-dose vaccines have been described in the medical literature as a possible strategy because their efficacy reduction is typically not commensurate with the level of fractionation, allowing greater population coverage. We seek to determine the optimal use and potential benefits of a fractionated vaccine dose with lower and more uncertain efficacy, given the specific supply constraints faced by a country.
Methodology: We employ a Susceptible-Infected-Recovered (SIR) epidemic model integrating vaccination with full- and fractional-doses over time. We embed it within a deterministic optimal control model aimed at identifying vaccination policies that minimize total infections during an epidemic, given operational constraints restricting the stockpile, delivery rate and administration of vaccines. Using a statistical approach described in the clinical literature for estimating the uncertainty around fractional-dose efficacy, we conduct two application case-studies grounded in real-world scenarios.
Results: Our theoretical analysis provides an intuitive characterization of the optimal vaccination policy which, depending on the epidemic and operational parameters, may utilize a combination of full- and fractional-dose vaccines, either simultaneously or sequentially. We also examine simpler policies that employ a single vaccine dosage throughout the epidemic. We conclude that, while these single-dose policies can often be almost as effective as the optimal policy in averting infections, they are not as robust to the uncertainty affecting fractional-dose vaccine efficacy.
Managerial implications: Fractional-dose vaccines, used either alone or in conjunction with full-dose vaccines, present an opportunity to significantly reduce infections during an epidemic in resource-constrained settings. The proportion of fractional-dose vaccines relative to full-dose vaccines in a campaign should generally increase with the maximum vaccine administration rate and decrease with the total antigen stockpile available.

© 2025, INFORMS

We study the pricing of homogeneous products sold to customers who consider different sets of suppliers. We identify prices that are stable in the sense that no firm wishes to undercut a rival or to raise its price when rivals are able to respond by offering special deals. We derive predictionsforstable and disperse prices acrossseveral price-consideration specifications, and we contrast the implications with those of conventional approaches.

[This paper supersedes working papers Stable Price Dispersion (2024) and A Theory of Stable Price Dispersion (2019).]

© 1999-2026 John Wiley & Sons, Inc

Although the topic of career regrets is of interest both to research and practice, the scholarly development of this field is still rather nascent. In particular, the knowledge about the occurrence and development of career regrets remains to be limited. Drawing on the qualitative data collected through individual reflections (N=50) and semi-structured interviews (N = 22), we explore the nature of an individual’s career regrets and how a career decision becomes a regret. Our findings suggest a broader understanding of career regrets that spreads beyond regrets that are tied to occupational choices. In line with this broad understanding of career regrets, we develop a framework of a career decision becoming a career regret. Our findings also show that when people reflect on career decisions in terms of how they should have behaved differently, there are some that they perceive as career regrets while others take a form of career mistakes or career realizations. We distinguish these different ways of viewing career decisions, suggesting that the latter two kinds of decisions are more influential in shaping an individual’s future career decisions than career decisions that are career regrets. Our research has important theoretical and practical implications concerning career regrets.

With permission of Emerald

We generalize the captive-and-shopper model of sales to allow asymmetries in production costs and captive audiences in an oligopoly. Both kinds of asymmetry determine the firms that compete (via randomized sales) to serve the price-comparing shoppers, while other firms exploit their captive audiences. In contrast to a model with symmetric costs (but asymmetric captive audiences) there are natural situations in which more than two firms use sales by engaging in pairwise battles across different price intervals. We then study the choice of production technologies via costly process innovations. A distinctive asymmetry emerges endogenously: one firm innovates more and becomes the dominant supplier of shoppers. The pattern of innovations connects to the size of firms’ captive bases and the shape of technological opportunity. We also provide a trio of extensions to consider costly acquisitions of captives and shoppers, and captives’ choice of captor.

Copyright ©2025 by the American Economic Association.

Large, generalist, technology firms—so-called “big-tech” firms—powerful in their primary market, routinely enter secondary markets consisting of specialist firms. Naturally, one might expect a specialist firm to be fiercely protective of its data as a way to maintain its market position in the secondary market. Counter to this intuition, we demonstrate that a specialist firm willingly shares its market data with an intruding generalist. We do so by developing a model of cross-market competition in which the data collected via consumer usage in one market can improve product quality in another. We show that a specialist firm shares its data to strategically create codependence between the two firms, thereby softening competition and transforming the generalist firm from a traditional competitor into a coopetitor. For the generalist intruder, data from the specialist firm substitute for its own investments in product quality in the secondary market. As such, the act of sharing data makes the generalist a stakeholder in the data collected by the specialist, and consequently in the specialist’s continued success. Moreover, although the firms benefit from data sharing, consumers can be worse off from weakened price competition and lower investments in innovation. Our results have managerial and policy implications, notably on account of backlash against data collection and the market power of big-tech firms.

© 2026, INFORMS