Table 3.
Results for the final mixed-effects logistic regression model evaluating the effect of L. salmonis output pressure (Xi,t) from the study farms on the log-odds of the presence of infestation with lice on out-migrating Chum salmon (Y) in Muchalat Inlet, during 2007–2016.
| Variable | Coefficient | 95% CI | P-value |
|---|---|---|---|
| Fixed effects | |||
| Xi,t | 1.08 | 0.46; 1.70 | 0.001 |
| Xi,t2 a | −0.18 | −0.35; −0.02 | 0.029 |
| Month | <0.001b | ||
| March | Ref.c | — | — |
| April | 2.27 | 1.29; 3.25 | <0.001 |
| May | 2.32 | 1.29; 3.34 | <0.001 |
| June | 0.38 | −0.95; 1.71 | 0.576 |
| Constant | −2.44 | −3.49; (−1.39) | <0.001 |
| Random effect variances | ICCd | 95% CI | P-value |
| Year | 0.21 | 0.07; 0.47 | <0.001 |
aXi,t2 is the quadratic term for the main predictor of interest (Xi,t: standardized output pressure of sea lice). The overall P-value for Xi,t and Xi,t2 was 0.0019.
bThe overall P-value for the month effect.
cReference category.
dICC: intra class correlation coefficient.