“…In this paper, we develop an R package ncpen for the non-convex penalized estimation based on the convex-concave procedure (CCCP) or difference-convex (DC) algorithm (Kim et al, 2008;Shen et al, 2012) and the modified local quadratic approximation algorithm (MLQA) (Lee et al, 2016). The main contribution of the package ncpen is that it encompasses most of existing non-convex penalties, including the truncated ℓ 1 (Shen et al, 2013), log (Zou and Li, 2008;Friedman, 2012), bridge (Huang et al, 2008), moderately clipped LASSO (Kwon et al, 2015), sparse ridge (Huang et al, 2013;Kwon et al, 2013) penalties as well as the SCAD and MCP and covers a broader range of regression models: multinomial and Cox models as well as the GLM. Further, ncpen provides two unique options: the investigation of initial dependent solution paths and non-standardization of input variables, which allow the users more flexibility.…”