Present-day oxygen abundance vs. M_∗ as predicted by models without wind. The upper (middle/lower) panel shows the model results with different numbers of bursts (durations/SFE), along the dashed blue lines the number of bursts (durations/SFE) increases from 2 to 7 (0.02 to 0.3/ 0.1 to 2), and along the solid black lines the total infall mass M_inf increases from 10⁸ to 10¹⁰ M_⊙. The thick solid red line connects the models that are consistent with the observational data, larger n (d/ϵ) for more massive galaxy. The observational data are the same as in Fig. 1, open cyan circles for BCDs and open cyan triangles for dIrrs.