Table 1.

Parameter values of the two limit cases of the general unified threshold model for survival (GUTS), stochastic death (SD) and individual tolerance (IT), after calibration to raw data from the fish acute toxicity test

Parameter	Units	Best fit value	95% confidence limits
GUTS-SD, carp (–∑ln likelihood = 14.5694, h_controls = 0.018 [1/d])
ke	1/d	1.00	0.82, 1.29
kk	L/(µg × d)	1.42	0.72, 2.52
z	µg/L	4.06	3.58, 4.42
GUTS-IT, carp (–∑ln likelihood = 15.0071, h_controls = 0.018 [1/d])
ke	1/d	0.47	0.40, 0.54
α	µg/L	3.63	3.30, 4.03
β	–	10.52	5.60, 21.9
GUTS-SD, fathead minnow (–∑ln likelihood = 16.7797, h_controls = 0.0035 [1/d])
ke	1/d	1.28	0.87, 2.64
kk	L/(µg × d)	0.42	0.20, 0.77
z	µg/L	3.85	3.25, 4.20
GUTS-IT, fathead minnow (–∑ln likelihood = 18.5279, h_controls = 0.0035 [1/d])
ke	1/d	0.47	0.34, 0.65
α	µg/L	3.97	3.33, 4.81
β	–	5.54	2.85, 9.54