Evolution of the slope for the magnetograms from the braid model simulations of Prior & MacTaggart (2016). The slope values are plotted against the normalised flux, defined in Eq. (1), which characterises the evolutionary phase. These simulations are not symmetric, and the positive (+) and negative (–) distribution slopes are plotted separately for the thick and thin braid models. The observational trend is shown by the dashed black line, and the approximate range of observed slope values is indicated by the grey shaded region.