Table 4. Biphasic models, kinetic parameters and statistical indices in the prediction of radical scavenging activity of pumpkin seed oil.

Model/parameter	Oil sample
	CP1	CP2	RS1	RS2	RS3	RS4	RS5	S1	S2
Weibull distribution model
kα	4.054	2.629	0.813	4.479	2.370	2.907	1.866	1.863	2.668
β	–0.550	–0.606	–0.249	–0.436	–0.413	–0.333	–0.311	–0.627	–0.685
R2	0.9999	0.9995	0.9999	0.9998	0.9994	0.9986	0.9984	0.9947	0.9983
SRMSE	0.012	0.023	0.006	0.014	0.025	0.036	0.039	0.077	0.001
χ2 error	0.96	1.93	0.47	1.17	2.08	2.97	3.28	6.37	0.03
First-order double-exponential model
k1	0.067	0.417	3.671	0.484	0.866	0.953	0.239	0.431	0.356
k2	0.307	0.131	0.186	0.094	0.160	0.217	1.302	0.072	0.069
R2	0.9999	0.9999	0.9999	0.9995	0.9997	0.9999	0.9999	0.9999	0.9988
SRMSE	0.008	0.003	0.008	0.022	0.018	0.003	0.009	0.011	0.037
χ2 error	0.73	0.27	0.73	1.96	1.62	0.28	0.82	0.97	3.34
Gustafson and Holden model
kα	0.564	0.651	0.175	0.336	0.315	0.226	0.216	0.536	0.705
β	3.207	2.580	0.065	1.423	0.675	0.399	0.238	1.146	2.554
R2	0.9998	0.9996	0.9999	0.9998	0.9954	0.9992	0.9990	0.9966	0.9973
SRMSE	0.015	0.012	0.010	0.070	0.021	0.028	0.030	0.060	0.054
χ2 error	1.30	1.70	0.84	5.94	1.77	2.34	2.56	5.08	4.59

k₁ and k₂=rate constants, k_α and β=shape and location parameters, R²=determination coefficient, SRMSE=scaled root mean square error, χ² error=error of chi-square test. For oil sample abbreviations see Table 1