Table 1.

Interaction of oocyst an sporozoite parameters (infection rate, oocyst number and absorbance) between assay, genotype (RR, RS and SS) and genotype-strain

Analysis	Variable		Df	Statistic	p
Oocyst infection rate	Assay		4	LRT = 0.51	0.97
	Genotype-strain		2	χ2 = 0.26	0.88
	Genotype		2	χ2 = 177.9	< 2.2e-16
	Strain		1	χ2 = 2.7	0.1
Sporozoite infection rate	Assay		4	χ2 = 0.94	0.92
	Genotype-strain		2	χ2 = 1.9	0.39
	Genotype		2	χ2 = 151.7	< 2.2e-16
	Strain		1	χ2 = 1.4	0.23
Oocyst number	Assay (random)	fem	6	AIC = 2,782	-
		mm	8	AIC = 2,668
	Genotype-strain		2	χ2 = 21.26	2.415e-05
	Genotype		No test needed since the interaction is significant
	Strain
Absorbance (Sporozoite density)	Assay (random)	fem	8	AIC = -141	-
		mm	7	AIC = -157
	Genotype-strain		2	χ2 = 0.82	0.66
	Genotype		2	χ2 = 81.5	3.291e-16
	Strain		1	χ2 = 11.3	0.0008

Random variables’ significance was evaluated by comparing the Akaike information criterion (AIC) of the most complex model, which included the random effect (mm, mixed model), and that of the same model with the random effect removed (fem, fixed-effect model). The model with the lowest AIC was chosen, i.e., the random effect was kept if the model in which it was included had the lowest AIC. The significance of fixed-effect variables was tested in a Chi-square test in the linear model of absorbance or a likelihood ratio test (which assumes a Chi-square distribution) in glm (generalized linear model), i.e., the three other analyses. The fixed-effect variable was considered significant and kept in the model if p <0.05 (in bold).