I was looking at a research paper the other day. In the paper they described some of the results from an experiment. They looked at two of the variables recorded in the experiment, mass and velocity. They looked at mass independently. First, they took the median of the mass. They then had two regions for mass in which they calculated the means of these two regions and looked at the ratio of the means of the regions w.r.t. the mean of the whole mass. This ratio was bounded for several experiments. I was wondering what this statistic meant. Where does it come from and what does it tell us?