Distribution of R_PAH^* vs. oxygen abundance for the entire sample of H II regions (gray histogram with intensity tracing the probability density), and average distribution for two bins in log([S III]/[S II]). The dashed lines are the same as in Fig. 1. The black squares represent measurements for WLM, NGC6822 (as in Fig. 1), the SMC, and the LMC from Chown et al. (2025a), listed in order of increasing metallicity. Spitzer IRAC4 and MIPS24 filters were used to estimate R_PAH^* for the SMC and LMC (Chown et al. 2025a).