Mutual information as a tool for measuring the amount of dependency between two variables is used in many applications in probability theory. In this paper, three mutual measures based on three aggregate uncertainty (AU) measures in Dempster–Shafer theory (DST) are proposed. These uncertainty measures are: 1) AU; 2) ambiguity measure (AM); and 3) modified AM (MAM), which is proposed in this paper. MAM is the modification of AM which resolves the nonsubadditivity problem of AM. A threat assessment problem constructed by a Dempster–Shafer network is used for testing these mutual measures. We use the proposed mutual measures to identify which input variables of the network are more influential on the threat value. Finally, we conclude that mutual uncertainty based on MAM is a justifiable measure to compute the dependency between two variables in applications related to the DST.

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