Observed evolution of the slopes. The emerging and decaying phases are distinguished by the function f(F/F_max) defined by Eq. (1), where F is the magnetic flux averaged between the two magnetic polarities, and F_max is its maximum value. The green points show individual distribution slope values obtained during the evolution of the leading and following magnetic polarities for 24 active regions. The red line shows the general trend (second-order polynomial least-squares fitted to the data points). The grey shaded area gives an indication of the spread of the data points. This summarises the main results of Dacie et al. (2016).