The second type, the non-additive synergy, is of three main categories: superadditive (I > 0 in Eq. 1), subadditive (I < 0 in Eq. 1), and isolated synergies (I depends on the specific set of x's considered in Eq. 1).
The third type of the non-additive synergy, the isolated synergy, is where the interaction between the interventions is the main focus irrespective of their individual effects (von Eye et al. 1998), for example, in chemical reactions.
Biochar and earthworm effects on rice growth and resource allocation highly depended on soil type and were generally additive (no synergy).
Three possible outputs are offered by the model: additive results, synergy and antagony.
There was no interaction on the multiplicative scale (interaction P = 0.634) or the additive scale (synergy index 1.14 [95% CI 0.48 1.79]).
Measure of effect modification on the additive scale: Synergy Index = 4.5 (95% CI = 0.9 to 21.6; P = 0.06).
ICR values greater than zero indicate greater than additive effects (synergy), and 95% CIs for the ICR that exclude zero can be used as a test for statistical significance at an alpha level of 0.05.
For the SNPs that remained significant, we also assessed interaction on the additive scale (synergy) by testing whether the estimated joint effect of As exposure and the at-risk SNP genotype(s) was greater than the sum of the independent effect estimates for As exposure and the SNP, respectively.
L and S are slightly super-additive, a synergy.
This analysis grouped the cell lines into three categories: antagonism (n=5, CI 1.10-3.3), neadditiveitive or slight synergy (n=5, CI 0.7-1.10), and synergy or strong synergy (n=2, CI <0.7) (Table 1).
