Representativeness of the stacked samples. Normalized distribution of some key physical properties, i.e., redshift (top left), stellar mass (top right), UV luminosity (bottom left), and UV spectral slope (bottom left) in our parent sample (green; “Par.”), our stack samples, including (red; “All”) and excluding the ALMA primary targets (“Off”), and the sub-sample of only the ALMA primary targets (yellow; “Targ.”). In each panel, we provide the p-value from the two-sample Kolmogorov-Smirnov (KS) analysis performed between these different samples and our parent sample.