 Plugging in the numbers from  Table 1  to calculate the overall recovery rates via these equations, we see that the first line is a weighted average of success rates for treated men and women (61% and 44%) while the second line is a weighted average of success rates of the two control groups (57% and 40%). These averages are weighted by the percentage of males and females in each group, and in the present case the gender disparity between the groups results in both averages being 50%. Since these weights can be different, the treatment may raise the probability of success among males and females without doing so in the combined population.