Table 3. Results of a generalized linear model (GLM) identifying factors affecting whether the bullfrog Lithobates catesbeianus rejected the bombardier beetle Pheropsophus occipitalis jessoensis.
| Response variable | Explanatory variable (fixed effect) | Coefficient estimate | SE | t value | P value |
|---|---|---|---|---|---|
| Rejectiona | Intercept | 11.68 | 7.466 | 1.564 | 0.12418 |
| Beetle treatmentb | −5.389 | 1.673 | −3.222 | 0.00226 | |
| Beetle size (weight) | −0.02395 | 0.0308 | −0.777 | 0.44061 | |
| Frog size (weight) | −0.0007511 | 0.000699 | −1.075 | 0.28783 | |
| Beetle size × frog size | 0.000002211 | 0.000003243 | 0.682 | 0.49872 |
Notes:
a
A quasi-binomial error distribution (rather than a binomial error distribution) was used because the residual deviance was smaller than the residual degrees of freedom.
b
Control beetles were used as a reference.