An easy parameter estimation by the EM algorithm in the new up-and-down method

Flashover voltage estimation has been carried out conventionally with the up-and-down method by Dixon and Mood. Recently, Hirose and Kato proposed a new version of the method to change the way of analyzing data. Although the method has better properties than the conventional one, it requires solving maximum likelihood equations. In this paper we reduce the troublesome task (e.g. implementation and the selection of a proper initial value) attendant on the requirement by using the expectation-maximization (EM) algorithm that gives a useful iterative formula to solve the equations. The iterative formula almost always can give the solutions of the likelihood equations because of its excellent global convergence of the EM algorithm.