Why do some patents get licensed while others do not?

Why do some orthodontic treatments last so long while others do not?

Social Learning with Payoff Externality: Why Some Learn While Others Do Not

This paper studies a model of social learning with externalities and possibly with limited observability of past actions. Bayesian agents sequentially choose an action each, after observing the actions of a subset of preceding agents. These actions and a private signal, conditionally independent across agents, supply information about the common state of the world. Each agent’s payoff depends o...

Why do bacterial plasmids carry some genes and not others?

Previous explanations of why bacterial genes for certain "optional" traits tend to occur on plasmids rather than chromosomes are based on an outdated misunderstanding of natural selection. They also fail to explain why certain characters that are ubiquitous in some bacterial species tend to occur on plasmids. This paper shows that all major classes of traits usually associated with plasmids rat...

Understanding the Paradox in Math-Related Fields: Why Do Some Gender Gaps Remain While Others Do Not?

Despite the ubiquity of harmful math attitudes that disadvantage girls, girls are now performing just as well as boys in math in the U.S. (Hyde et al. 1990; Hyde et al. 2008). At the same time, stark gender disparities remain in who chooses to pursue math-related careers (National Science Foundation 2009). Why have gender disparities persisted in some math-related domains but not others? I sugg...

Why do some overweight children remain overweight, whereas others do not?

OBJECTIVE To study the dynamics of childhood overweight and the influence of dietary intake on tracking of overweight. DESIGN AND SETTING A follow-up study conducted in China. SUBJECTS Ninety-five overweight children, 6-13 years old, identified from 1455 children at baseline, were followed over a 2-year period. METHODS Data on anthropometry and 3-day dietary intake were collected at basel...