Precision, recall, and F1-score for various methods of identifying quiescent galaxies. We show results for the three cases discussed in Sect. 5.1: (i) Euclid Deep Survey photometry with supporting ugriz, W1 , W2, and 20 cm photometry; (ii) Euclid Wide Survey photometry with supporting ugriz, W1 , W2, and 20 cm photometry; and (iii) Euclid Wide Survey photometry only. Two curves are shown for the Euclid-only case, corresponding to results obtained either with or without foreknowledge of the galaxy redshifts. All other results shown in this figure were obtained assuming foreknowledge of redshifts. In addition, we show the result of applying the I_E − Y_E, J_E − H_E colour-colour selection method developed by B20, assuming foreknowledge of (photometric) redshifts. In this and subsequent plots showing metrics vs. redshift, the x axis represents the 'ground truth' photometric redshifts from COSMOS2015 (Laigle et al. 2016).