A classical measure of evidence for general null hypotheses

In science, the most widespread statistical quantities are perhaps p-values. A typical advice is to reject the null hypothesis H0 if the corresponding p-value is sufficiently small (usually smaller than 0.05). Many criticisms regarding p-values have arisen in the scientific literature. The main issue is that in general optimal p-values (based on likelihood ratio statistics) are not measures of evidence over the parameter space Θ. Here, we propose an objective measure of evidence for very general null hypotheses that satisfies logical requirements (i.e., operations on the subsets of Θ) that are not met by p-values (e.g., it is a possibility measure). We study the proposed measure in the light of the abstract belief calculus formalism and we conclude that it can be used to establish objective states of belief on the subsets of Θ. Based on its properties, we strongly recommend this measure as an additional summary of significance tests. At the end of the paper we give a short listing of possible open problems.