Comparison of two measurements from two different spectra for 11 SL2S galaxy. The other spectrum for the same galaxy is either from a different instrument or a different observing night with the same instrument. The σ_{high S/N} is our fiducial measurement, and σ_{low S/N} is the second-best measurement. The solid line shows the mean, and the dashed lines show the 1σ uncertainty of the mean.