Distribution of parameters of 19 confirmed SMC SNRs using kernel smoothing. The colour of symbols indicate progenitor type for a particular SNR. Data points that fall in the same bin on the x-axis are plotted within a vertical column with equidistant spacing. The upper and lower grey curves delineate the 95% uncertainty level. The corresponding kernel bandwidth h and distribution parameters are shown on each panel. Top left: average diameter distribution. Top right: distribution of ovality, which is defined as 2 (D_maj − D_min)∕(D_maj + D_min), where D_maj and D_min are the major and minor axes, respectively. Bottom left: radio spectral index distribution. Bottom right: estimate of the 1 GHz flux density distribution for the 18 SNRs with available 1 GHz flux density estimates from Table A.1.