The joint probabilities method was introduced by Pugh and Vassie to enable estimates of the probability of extreme sea levels to be obtained from short data sets. Since the introduction of the method, a number of deficiencies with the approach have been identified, which affect its application; these are discussed. On the basis of relevant work in statistical extreme value theory, some refinements are suggested, and, by means of examples, are shown to be a significant improvement over the existing method.