Table 2 Values that were considered to categorize explanatory variables in the negative binomial regression
Explanatory variables | Exposure | Values |
|---|---|---|
FC | ||
 1 | Yes | 30–70% |
 0 | No | 0–30% or 70–100% |
ED | ||
 1 | Yes | 0.0149 to 0.0292 (3rd and fourth quartiles, respectively) |
 0 | No | 0.0077 to 0.0141 (first and second quartiles, respectively) |
DW | ||
 1 | Yes |  ≤ 138 m (median) |
 0 | No |  > 138 m (median) |