I have studied few papers on performance degradation assessment of several components where the researchers calculate a confidence value based on the overlap ratio for assessing the health of components: (Please refer to the paper):

http://www.sciencedirect.com/science/article/pii/S0307904X15002309

Though training the gaussian mixture models could be easily implemented in Matlab, I am finding it very difficult to the calculate the overlap ratio between normal state and degraded state conditions. Please help me to solve the problem.