PAH mass fraction as a function of galaxy parameters. From top-left to bottom-right: age of the galaxy, SFR, stellar mass, obscured luminosity fraction, SFR surface density (using F1500W sizes). The robust sample is shown with a teal colour and the low-confidence sample with smaller grey symbols (see Section 2.2 for sample definitions). The moving medians of the full (robust+low-confidence) and robust samples are shown as grey and black curves, respectively. In the bottom row, the unresolved sources in F1500W images are shown with triangles as lower limits on SFR surface density. Among the parameters show, q_PAH has the strongest correlations with mass, age, and obscured luminosity fraction.