(A) Maximum Likelihood Estimates | ||||
Model | Model No. | df | dev | AIC |
pcr ~ method + season + year + stage + season:stage | 1 | 308 | 165.77 | 189.77 |
pcr ~ method + season + year + stage | 2 | 311 | 172.95 | 190.95 |
pcr ~ season + year + stage | 3 | 312 | 191.10 | 207.10 |
pcr ~ method + year + stage | 4 | 313 | 180.54 | 194.54 |
pcr ~ method + season + stage | 5 | 314 | 181.75 | 193.75 |
pcr ~ method + season + year | 6 | 313 | 183.51 | 197.51 |
(B) Likelihood ratio tests | ||||
Effect | Comparison | Δ df | Δ dev | p |
season:stage | 1 vs. 2 | 3 | 7.18 | 0.066 |
method (swab vs. other methods) | 2 vs. 3 | 1 | 18.15 | <0.001 |
season (spring, summer, fall) | 2 vs. 4 | 2 | 7.59 | 0.022 |
year (2003, 2005, 2006, 2007) | 2 vs. 5 | 3 | 8.80 | 0.032 |
stage (yoy, juvenile, adult) | 2 vs. 6 | 2 | 10.56 | 0.005 |
(C) Parameter estimates | ||||
Factor | Estimate | s.e. | z | p |
Intercept | -4.159 | 1.241 | -3.351 | <0.001 |
method: swab | -2.028 | 0.488 | -4.157 | <0.001 |
season: summer | -1.888 | 1.125 | -1.679 | 0.093 |
season: fall | 0.549 | 0.707 | 0.777 | 0.437 |
year: 2005 | 2.099 | 0.900 | 2.333 | 0.020 |
year: 2006 | 2.528 | 1.015 | 2.490 | 0.013 |
year: 2007 | 2.704 | 1.059 | 2.554 | 0.011 |
stage: juvenile | 1.705 | 0.816 | 2.089 | 0.037 |
stage: adult | 1.976 | 0.610 | 3.239 | 0.001 |