χ² contour levels for the dlog (φ)/dz, parameters derived for the Schechter–like LF considering all four Hawk-I fields. The lower and left axis refer to the evolutionary terms and dlog (φ)/dz with respect to the best-fit z = 6 parameters of McLure et al. (2009) (black point and errorbars). The upper and right axis refer to the M _∗  and φ values at the median redshift estimated for our sample (z = 6.8). Grey points and errorbars mark the position of the z ~ 7 best-fit parameters by Ouchi et al. (2009a) and by Bouwens et al. (2008). The black solid line indicates the 99% c.l. region estimated on the basis of the two GOODS-South pointings only (C10).