Figure 1. The allometric relationship between the brain and body sizes in 1309 mammalian species.

Because the families were represented by an unequal number of data points (species), each family was given an equal weight when calculating the ordinary least-square regression. This correction for biased representation of the families resulted in a line seemingly unfitting the data points (representing species and not families). This adjusted regression line is considerably more reliable for further GLM analyses performed between family level, though. Allometric equation: ln(brain mass) = −0.6601 * ln(body mass)−2.4100.