Fraction of star-forming galaxies in different environments, computed with sSFR (left panel) and rest-frame colour (right panel). The fractions obtained using the magnitude-limited sample are represented with filled symbols and solid errors, those obtained using the mass-limited sample are represented by empty symbols and dashed error bars. Errors are derived by means of a bootstrap method. The two lower panels show the quenching efficiency (Q.E.) in different environments, computed with Eq. (3) for both the star-forming and blue samples. The Q.E. of field galaxies, which is by definition set to zero (see Eq. (3)), is shown in both panels as a reference. The error bars on the Q.E of the low-density field depend on the amplitude of the confidence intervals associated with the fractions of star-formingand passive galaxies from bootstrapping.