Table 1. Results of a generalised linear model (GLM) testing potential factors influencing whether the frog Pelophylax nigromaculatus successfully swallowed the bombardier beetle Pheropsophus jessoensis in feeding experiments.

Response variable	Explanatory variable (fixed effect)	Coefficient estimate	SE	t value	P value
Swallowing successa	Intercept	7.601881	4.454207	1.707	0.094
	Frog weight	−0.420817	0.290774	−1.447	0.154
	Beetle weight	−0.060781	0.025084	−2.423	0.019
	Frog weight × Beetle weight	0.002637	0.001457	1.81	0.076c
	Beetle treatmentb	1.387536	0.855616	1.622	0.111

Notes.

^aAs the residual deviance was smaller than the residual degrees of freedom, a quasi-binomial error distribution (rather than a binomial error distribution) was employed. Two and four live and dead beetles, respectively, were swallowed.

^bLive beetles were used as a reference.

^cThe significance of this factor was checked using the likelihood ratio test (P = 0.063).