From lidar signals detected with a shot/shot differential absorption lidar instrument tuned for tropospheric O3 measurements and recording each individual return, histograms of their sampled values for each channel of their digitizers were reconstructed. Anal. of their shape permits correction of measurements for exptl. biases. In particular, a neg. correlation was obsd. between the histogram skew and the intensity of backscattered light. The skew comes from a tail at high sampled values, interpreted as due to a raise of the relative contribution to the signal of a signal-induced noise when this intensity diminishes. By fitting a Gaussian function to the histograms without considering their tails, av. signals unbiased by the corresponding noise were calcd. This approach allows an increase the range of O3 profiles, up to as much as double, in some cases.