Use behavioral research to improve the feasibility and effectiveness of system-level policy.

Individual-level interventions are inadequate to address complex societal problems. Meaningful solutions require system-level policies that alter the incentives that govern behavior. We argue that individual-level interventions can help improve both the feasibility and effectiveness of system-level interventions, especially when designed as an integrated policy package.

Create a culture of experiments in environmental programs.

Organizations need a better "learning by doing" approach.

Frequent mandatory COVID-19 testing may increase risky behavior.

Mandatory surveillance testing programs are popular policies aimed to control SARS-CoV-2 and may be considered for future epidemics. However, if people believe that testing lowers their risk of infection, such policies could increase risky behavior and may even cause increased pathogen spread. Using data from two US universities, we find that frequent mandatory testing is associated with greater participation in events linked to COVID-19 spread. Women seem to be driving this association, and mediation analyses suggest this is partly due to women's higher perception of COVID-related health risks. Our results show the potential for adverse effects from epidemic control policies, both on average and across population subgroups. Undertaking mitigation measures to reduce such unintended consequences may therefore be important.

Emphasize personal health benefits to boost COVID-19 vaccination rates.

The rapid development of COVID-19 vaccines is a tremendous scientific response to the current global pandemic. However, vaccines per se do not save lives and restart economies. Their success depends on the number of people getting vaccinated. We used a survey experiment to examine the impact on vaccine intentions of a variety of public health messages identified as particularly promising: three messages that emphasize different benefits from the vaccines (personal health, the health of others, and the recovery of local and national economies) and one message that emphasizes vaccine safety. Because people will likely be exposed to multiple messages in the real world, we also examined the effect of these messages in combination. Based on a nationally quota representative sample of 3,048 adults in the United States, our findings suggest that several forms of public messages can increase vaccine intentions, but messaging that emphasizes personal health benefits had the largest impact.

The impact of public health messaging and personal experience on the acceptance of mask wearing during the COVID-19 pandemic.

Face coverings have been shown to slow the spread of COVID-19, yet their use is not universal and remains controversial in the United States. Designing effective nudges for widespread adoption is important when federal mandates are politically or legally infeasible. We report the results from a survey experiment in which subjects were exposed to one of three video messages from President Trump, and then indicated their preference for wearing a mask. In the first video, the President simply recited the Centers for Disease Control and Prevention (CDC) guidelines. In the second, the President additionally emphasized that wearing a mask is optional. In the third video, the President added that he will not personally wear a mask. We find that exposure to presidential messages can increase the stated likelihood of wearing a mask-particularly among the President's supporters. We also explore experiential effects of COVID-19, and find that people (especially supporters of the President) are more likely to support wearing a mask if they know someone who has tested positive for COVID-19. These results offer guidance to policy makers and practitioners interested in understanding the factors that influence viral risk mitigation strategies.

Climate change impacts on crop yield: evidence from China.

When estimating climate change impact on crop yield, a typical assumption is constant elasticity of yield with respect to a climate variable even though the elasticity may be inconstant. After estimating both constant and inconstant elasticities with respect to temperature and precipitation based on provincial panel data in China 1980-2008, our results show that during that period, the temperature change contributes positively to total yield growth by 1.3% and 0.4% for wheat and rice, respectively, but negatively by 12% for maize. The impacts of precipitation change are marginal. We also compare our estimates with other studies and highlight the implications of the inconstant elasticities for crop yield, harvest and food security. We conclude that climate change impact on crop yield would not be an issue in China if positive impacts of other socio-economic factors continue in the future.