The GEIG metric for quantifying the accuracy of parsing became influential through the Parseval programme, but many researchers have seen it as unsatisfactory. The Leaf-Ancestor (LA) metric, first developed in the 1980s, arguably comes closer to formalizing our intuitive concept of relative parse accuracy. We support this claim via an experiment that contrasts the performance of alternative metrics on the same body of automatically-parsed examples. The LA metric has the further virtue of providing straightforward indications of the location of parsing errors.