Areas of 68% confidence derived on the Schechter parameters when testing different binnings. Left panel: results for 2.9 <  z <  4.0 and the right panel those for 5.0 <  z <  6.7. The legends on the plots indicate, from left to right, log(L)_min, log(L)_max and the number of bins considered for the fit between these two limits. The black lines show the results obtained from the optimal bins adopted in this work.