Mean abundance ratios as a function of cosmic-ray ionization rate for five diagnostic species: CS, CH₃SH, H₂CO, HCO⁺, and NS⁺. Each panel shows ratios for four physical environments: protostellar objects (solid orange lines), warm-up (dashed orange lines), shocks (solid gray lines), and post-shock (dashed gray lines). Neutral-to-ion ratios (top two panels) generally decline by 3–4 orders of magnitude as log₁₀(ζ/ζ₀) increases from 1 to 4, but show distinct slopes between environments. The ion-to-neutral ratios (third and fourth panel) exhibits a clear trend in shock-related gas, increasing with increasing ionization rate. However, NS⁺/H₂CO also exhibits a consistent increasing trend in protostellar objects. The ion-to-ion ratio NS⁺/HCO⁺ (bottom panel) exhibits a shallower response, remaining relatively flat in shock-related gas, while declining more clearly in thermally processed gas.