TABLE 2.
Negative-binomial-regression model for the association between cattle type, beneficial management practices, and precipitation and concentration of Giardia spp. (cysts/liter) discharging from dairy cattle high-use areas during runoff conditions from 2002 to 2004 in Tomales Bay, CA
| Risk factor | Coefficient | 95% CIb | P valueb |
|---|---|---|---|
| Type of dairy cattle | |||
| Cow, milking or drya | 0.0 | ||
| Cow, calving | −3.54 | (−4.85, −2.23) | <0.001 |
| Calf, 2.1 to 6.0 mo of age | −0.18 | (−1.59, 1.23) | 0.80 |
| Calf: 0.1 to 2.0 mo of age | 4.18 | (2.50, 5.85) | <0.001 |
| Length of vegetated buffer (m) | −0.15 | (−0.22, −0.09) | <0.001 |
| Cumulative annual precipitation (mm) | −0.006 | (−0.009, −0.003) | <0.001 |
| Constant or intercept term for the model | 5.43 | (4.42, 6.44) | <0.001 |
a
Referent condition for the categorical variable, type of dairy cattle.
b
Adjusted for potential lack of independence due to repeated sampling of high-use areas across storms.