Evolution of the log ₁₀(SFR) dispersion as a function of both redshift and stellar mass. Each color is showing a different redshift bin. Filled symbols show the result of scatter stacking, while open symbols show the dispersion estimated from individual Herschel detections above the main sequence (see text). The open symbols have been shifted up by 0.1 dex in mass for clarity. Errors are from bootstrapping in all cases. We compare these to the typical scatter of the SFHs in the numerical simulation of Hopkins et al. (2014) shown as a solid purple line.