Standard Tukey box plot of the global time scale τ_global sampled at a fixed time interval throughout the simulations (left) Low1-9 and (right) Hi1-5. A box plot (e.g. Spitzer et al. 2014; McGill et al. 1978) is designed to show characteristics of the spread of the data. The line in the middle of the box is the median. The box itself represents the middle 50% of the data, so that the edges are the 25th and 75th percentiles. The whiskers, i.e. error bars, represent the extent of the data when outliers are discounted. Outliers are represented by circles. For a Tukey box plot, outliers are defined as data that lie farther than 1.5 times the interquartile range from the box. The vertical black line at 5 × 10⁶ s marks the value of τ_conv that we obtain from mixing length theory.