Top row: PDFs for the GW strain amplitude, contributed by a population of inspiraling SMBHBs at a frequency f = 1 yr⁻¹ (h_c; left) and the average merger time for the same population (﹩\langle {t}_{\mathrm{evol}}\rangle ;﹩ right). Both refer to the model h_c3, in which SMBHB masses are corrected for Malmquist bias. Bottom row: CDFs corresponding to the PDFs in the top row. Red lines mark the 95th and 5th percentile values of h_c and ﹩\langle {t}_{\mathrm{evol}}\rangle ﹩, respectively.