The Environmental Protection Agency answered another reader question about the cost differential between treating lead with a neutralizing additive versus carting the soil away.
In this case, a three-arm design would allow a very elegant prove of the additive versus non-additive model of the placebo response.
Drinking solutions containing 2 ppm concentrations of THF-diols or LTX-diols completely (100%) blocked estrus in rats, such that no definitive measure of LOAEL or mechanism(s) of action or interaction (additive versus synergistic) of the THF-diols or LTX-diols could be obtained.
A likelihood ratio test was used to determine which mode of inheritance (e.g., additive versus additive dominance) best fits the data.
Determination of the synergistic versus additive versus antagonistic-inhibitory effects of treatment combination was made using the isobologram of Steel and Peckham.
We also acknolwedge that the differentiation between an additive versus a multiplicative risk function has not been made in the Woodruff study nor in our risk assessment.
A long-standing controversy revolves around the relative importance of additive versus non-additive (dominance and epistatic) effects.
For the d/a ratio tests, estimates of the additive (a) and dominance (d) parameters were used to test the relative contribution of additive versus dominance effects in outbred recapture rates (Falconer 1989), where a = (PL − PF /2 and d = F1 − (PL + PF /2, with PL and PF being the recapture rates of the 'local' and 'foreign' pure cross types, respectively.
In analyzing the nature of this interaction (additive versus synergistic) it would have been desirable to construct dose response curves, but such experiments were not deemed acceptable in view of ethical considerations.
Likelihood ratio tests were applied as proposed by North et al. [ 17] to investigate both the modes of allelic action for both loci (additive versus dominance effects) and for possible epistatic effects (additive by additive, additive by dominance and dominance by dominance interactions).
Thirty multiparous lactating Friesian cows (523 ± 8.9 kg BW) were used to study the effect of feeding coriander oil, a natural feed additive, versus salinomycin; an ionophore.
