Figure 6From: A nonparametric model for quality control of database search results in shotgun proteomicsML function values and χ2 statistic with iterative step and different numbers of mixed Gaussian functions. n, the iterative step of the EM algorithm; L, the ML function value; chi-square, χ2 statistic; N, number of mixed Gaussian functions. It is clear that the EM algorithm will confront the local minimum problem when the number of variables is too many.Back to article page