Covid-related surge in global wild bird feeding: Implications for biodiversity and human-nature interaction.

The global extent of supplementary bird feeding is unknown but has consequences for bird conservation and human well-being. Using a measure of search intensity for words related to bird feeding from Google, we document a surge of interest in bird feeding that occurred around the world after Covid-19 led to lockdowns where people stayed home: 115 countries saw an increase in bird feeding search interest. We test whether the existence of interest in bird feeding is associated with greater species richness of bird species, our proxy for biodiversity, and find the relationship is highly significant. Covid-19 lockdowns may have persistent influences on global bird populations and humans' connection to nature.

The kids aren't alright: The effects of medical marijuana market size on adolescents.

We exploit shocks to US federal enforcement policy to assess how legal medical marijuana market size affects youth marijuana use and consequences for youth traffic-related fatalities. Using hand-collected data on state medical marijuana patient rates to develop a novel measure of market size, we find that legal market growth increases youth marijuana use. Likely mechanisms are lower prices and easier access. Youth die more frequently from alcohol-involved car accidents, suggesting complementarities for youths. The consequences of marijuana legalization for youth are not immediate, but depend on how supply-side regulations affect production and prices.

U.S. cannabis laws projected to cost generic and brand pharmaceutical firms billions.

Legalization of cannabis by U.S. states is likely increasing the use of cannabis as an alternative to conventional pharmaceutical drugs. We examined how cannabis legalization between 1996 and 2019 affected stock market returns for listed generic and brand pharmaceutical companies and found that returns were 1.5-2% lower at 10 days after legalization. Returns decreased in response to both medical and recreational legalization, for both generic and brand drugmakers. Investors anticipate a single legalization event to reduce drugmaker annual sales by $3B on average.

Urban forest biodiversity and cardiovascular disease: Potential health benefits from California's street trees.

Enhanced immune functioning in response to biodiversity may explain potential health benefits from exposure to green space. Using unique data on urban forest biodiversity at the zip code level for California measured from 2014 to 2019 we test whether greater diversity of street trees is associated with reduced death from cardiovascular disease. We find that urban forests with greater biodiversity measured via the Shannon Index at the genus level are associated with a lower mortality rate for heart disease and stroke. Our estimates imply that increasing the Shannon Index by one standard deviation (0.64) is associated with a decrease in the mortality rate of 21.4 per 100,000 individuals for heart disease or 13% and 7.7 per 100,000 individuals for stroke or 16%. Our estimates remain robust across several sensitivity checks. A policy simulation for tree planting in Los Angeles based on our estimates suggests that if these relationships were causal, investment in planting for a more biodiverse set of street trees would be a cost-effective way to reduce mortality related to cardiovascular disease in urban areas.

Using recreational cannabis to treat insomnia: Evidence from over-the-counter sleep aid sales in Colorado.

This study seeks to understand whether people substitute between recreational cannabis and conventional over-the-counter (OTC) sleep medications. UPC-level grocery store scanner data in a multivariable panel regression design were used to compare the change in the monthly market share of sleep aids with varying dispensary-based recreational cannabis access (existence, sales, and count) in Colorado counties between 12/2013 and 12/2014. We measured annually-differenced market shares for sleep aids as a portion of the overall OTC medication market, thus accounting for store-level demand shifts in OTC medication markets and seasonality, and used the monthly changes in stores' sleep aid market share to control for short-term trends. Relative to the overall OTC medication market, sleep aid market shares were growing prior to recreational cannabis availability. The trend reverses (a 236% decrease) with dispensary entry (-0.33 percentage points, 95% CI -0.43 to -0.24, p < 0.01) from a mean market share growth of 0.14 ±â€¯0.97. The magnitude of the market share decline increases as more dispensaries enter a county and with higher county-level cannabis sales. The negative associations are driven by diphenhydramine- and doxylamine-based sleep aids rather than herbal sleep aids and melatonin. These findings support survey evidence that many individuals use cannabis to treat insomnia, although sleep disturbances are not a specific qualifying condition under any U.S. state-level medical cannabis law. Investigations designed to measure the relative effectiveness and side effect profiles of conventional OTC sleep aids and cannabis-based products are urgently needed to improve treatment of sleep disturbances while minimizing potentially serious negative side effects.

Simpler is better: Predicting consumer vehicle purchases in the short run.

When agencies such as the US Environmental Protection Agency (EPA) establish future greenhouse gas emissions standards for new vehicles, forecasting future vehicle purchases due to changes in fuel economy and prices provides insight into regulatory impacts. We compare predictions from a nested logit model independently developed for US EPA to a simple model where past market share predicts future market share using data from model years 2008, 2010, and 2016. The simple model outperforms the nested logit model for all goodness-of-prediction measures for both prediction years. Including changes in vehicle price and fuel economy increases bias in forecasted market shares. This bias suggests price increases are correlated with unobserved increases in vehicle quality, changes in preferences, or brand-specific changes in market size but not cost pass-through. For 2010, past shares predict better than a nested logit model despite a major shock, the economic disruption caused by the Great Recession. Observed share changes during this turbulent period may offer upper bounds for policy changes in other contexts: the largest observed change in market share across the two horizons is 6.6% for manufacturers in 2016 and 3.4% for an individual vehicle in 2010.