Table 2. Ranking of 12 general mixed linear models relating the nest success of dabbling ducks as a function of country (Canada vs. United States), proportion cropland, pond density, and their interactions in North American prairies between 1964 and 1995. Each model had year and study site nested in survey strata as random effects. n = sample size; K = number of parameters; AICc = Akaike’s Information Criterion, corrected for small sample sizes; ΔAICc = the difference in AICc between each model and the model with the minimum AICc; w = Akaike weight, and r² = the proportion of the total variation in nest success explained by each model (Xu 2003).
| |
| |
|
Model |
Fixed effects |
-2*LL |
n |
K |
AICc |
ΔAICc |
w |
r² |
| |
|
1 |
Intercept only |
-76.8 |
218 |
4 |
-68.6 |
14.81 |
0.00 |
0.02 |
|
2 |
Country |
-79.6 |
218 |
5 |
-69.3 |
14.08 |
0.00 |
0.03 |
|
3 |
Pond Density |
-79.1 |
218 |
5 |
-68.8 |
14.62 |
0.00 |
0.04 |
|
4 |
Country + Pond Density |
-86.9 |
218 |
5 |
-76.6 |
6.77 |
0.01 |
0.09 |
|
5 |
Country + Pond Density + Country*Pond Density |
-86.9 |
218 |
6 |
-74.5 |
8.88 |
0.00 |
0.09 |
|
6 |
Proportion Cropland |
-92.5 |
218 |
6 |
-80.1 |
3.31 |
0.07 |
0.12 |
|
7 |
Country + Proportion Cropland |
-92.7 |
218 |
7 |
-78.1 |
5.26 |
0.03 |
0.12 |
|
8 |
Country + Proportion Cropland + Country*Proportion Cropland |
-92.7 |
218 |
7 |
-78.1 |
5.25 |
0.03 |
0.12 |
|
9 |
Country + Proportion Cropland + Pond Density |
-96.0 |
218 |
7 |
-81.4 |
1.94 |
0.13 |
0.13 |
|
10 |
Country + Proportion Cropland + Pond Density + Country*Proportion
Cropland |
-96.0 |
218 |
8 |
-79.3 |
4.05 |
0.05 |
0.13 |
|
11 |
Country + Proportion Cropland + Pond Density + Country*Pond
Density |
-100.1 |
218 |
8 |
-83.4 |
0.00 |
0.35 |
0.15 |
|
12 |
Country + Proportion Cropland + Pond Density + Country*Pond Density +
Country*Proportion Cropland |
-102.1 |
218 |
9 |
-83.2 |
0.15 |
0.33 |
0.16 |
|
| |
|