We assumed a multiplicative interaction effect on the logit scale.
Evidence of a multiplicative interaction effect at baseline and longitudinally was assessed in Cox proportional hazards models that included main effects and a multiple interaction term.
A multiplicative interaction effect between VPA and ATRA will be included in the logistic regression model and its size will be estimated with 95 %-confidence interval.
Interestingly, we detected a significant additive and multiplicative interaction effect between the LIG4 rs1805388 and XRCC4 rs1805377 polymorphisms with an increasing risk of gliomas.
To investigate the influence of gene-gene interactions on gene expression trait heritability, we selected genes presenting multiple eQTLs and for each selected gene we fitted a linear mixed model with incorporation of SNP-SNP multiplicative interaction effect.
However, in the estimation of multiplicative gene-environment interaction effect, Garcia-Closas et al.[ 57] showed that under a set of conditions typically satisfied in studies of gene-environment interactions, both differential and non-differential misclassification of a binary environmental factor biases a multiplicative interaction effect toward the null value.
Considering the study of a simple two-way interaction between an environmental factor and a rare MC1R variant, around 5,000 cases and 5,000 controls would be needed to observe a multiplicative interaction effect of 2.0, arising to 16,000 cases and 16,000 controls to observe a smaller multiplicative effect of 1.5, both with 90% statistical power.
Multiplicative interaction (effect modification) between the intervention ("Mediterranean diets," i.e., the two groups merged into one category) and age, sex, BMI, and baseline fasting glucose were assessed using the likelihood ratio test for multiplicative product terms introduced in fully adjusted Cox models.
In the multiple regression analyses multiplicative interaction effects were entered to explore whether early weight is modifying the effect of later weight size on adult overweight with a type I error rate of 0.10 [28].
For a number of genes with multiple eQTLs, we modelled multiplicative interaction effects and evaluated the contribution of gene-gene interactions to total gene expression heritability.
