Introduction
The central question Spotwood et al. investigated is the existence of an association between COVID-19 cases, nature accessibility, and other sociodemographic characteristics. They attempted to utilize ZIP-Code-scale data to examine whether the negative association between COVID- 19 case rates and greenness shown with county-level data in the United States still holds at the finer geospatial level.
The variables are all in the scale of ZIP Code Tabulation Areas (ZCTAs). The primary response variable is the number of COVID cases per 100,000 people between March and September 2020 (fetched on 1 October 2020). The explanatory variables include greenness, such as the Normalized Difference Vegetation Index (NDVI) and park access, and sociodemographic features, such as the proportion of White people and people of colour (POC), age, income, and population density. Notably, Spotswood et al. excluded rural areas from their analysis while we kept the rural data in our model. Furthermore, the "Urban" variable is the only binary variable in our dataset.
We hypothesized that more green space and higher income would lead to lower Covid-19 case rates. In order to test this hypothesis, we used Covid-19 case rates as our response variable, and selected median income, proportion of white residents, NDVI, percent parks, median age, and aridity, as well as the dummy variable urban, as our explanatory variables. We selected Arizona, Florida, and Maine as the states on which to conduct our analysis.
Summary statistics
We chose Florida (n=912), Arizona (n=353), and Maine (n=376) as the analysis target. The distributions of variables across different State varied (See Table1). Overall, Florida has the most COVID-19 cases rates (mean = 3064.34, median = 2611.34), Arizona the second (mean = 2645.94, median = 1968.03), and Maine the least (mean = 238.479, median = 149.115). The greenness also differ across states (mean = 0.32(AZ), 0.58(FL), 0.78(ME)), but the standard deviations (AZ 0.09, Fl 0.10, ME 0.04) show that the difference among each state is relatively small.