SSR as a function of a target I_AB magnitude. The dark green histogram shows the magnitude distribution of the targets from the total parent sample where a slit was positioned. The filled light green histogram shows the magnitude distribution of the targets whose redshift is reliably measured (for both histograms the numbers are indicated on the left Y axis). The filled points are the SSR, which is a ratio of the two histograms whose value is indicated on the right Y axis. The continuous light green curve is the adopted function to parametrize SSR(I_AB).