Distribution of likelihood ratios, LR, as defined by eq. (1). We compute the likelihood that a radio source has a given optical counterpart following de Ruiter et al. (1977), which is summarized in § 2.4. We show all radio sources which were positively identified with an optical counterpart as a solid distribution. The unidentified galaxies are represented as a hatched distribution. As argued in the text, every positively identified object has ﹩\mathrm{LR}\,\geq 2﹩, while the unidentified galaxies have ﹩\mathrm{LR}\,\ll 2﹩. Note that two objects with ﹩\mathrm{LR}\,> 40﹩ are not represented.