Density estimation using non-parametric and semi-parametric mixtures

This article presents a general framework for univariate non-parametric density estimation, based on mixture models. Similar to kernel-based estimation, the proposed approach uses bandwidth to control the density smoothness, but each density estimate for a fixed bandwidth is determined by non-parametric likelihood maximization, with bandwidth selection carried out as model selection. This leads to simple models, yet with higher accuracy, especially in terms of the Kullback–Leibler or the Hellinger risk. The particular problem of estimating a symmetric density function is investigated. Both simulation study and real-world data examples suggest that the mixture-based estimators outperform their kernel-based counterparts.