Fig. 2From: Theory of synergistic effects: Hill-type response surfaces as ‘null-interaction’ models for mixturesResponse surfaces (a–c) and isoboles (d–f) for binary mixtures. Effects are given in %. a, d Hill surface; b, e Bliss surface; c, f Difference plots u Hill −u Bliss show that u Bliss ≥u Hill . (Parameters: u min =0, a max =0.7, \(d_{a_{50}}=100\), α=1, b max =1.0, \(d_{b_{50}}=1\), β=2). Dashed lines denote the respective d 50 valuesBack to article page