“…In fact, principal points are applied to various problems, including product design and quality control problems, such as finding an optimal set of designs for masks (Flury, 1993), selective assembly for two parts in the manufacturing field (Mease et al, 2004;Mease and Nair, 2006;Matsuura, 2011), functional data analysis (Tarpey and Kinateder, 2003;Shimizu and Mizuta, 2007;Shimizu and Mizuta, 2008), and classification analysis of the placebo effect (Tarpey, et al, 2010). The properties of principal points have been widely studied in the literature (e.g., Tarpey and Flury, 1995;Zoppè, 1995;Yamamoto and Shinozaki, 2000;Gu and Mathew, 2001;Kurata, 2008;Bali and Boente, 2009;Matsuura and Kurata, 2011;Matsuura and Kurata, 2014), and the parametric estimation of principal points of some continuous distributions has also been discussed (e.g., Flury, 1993;Tarpey, 1997;Stampfer and Stadlober, 2002;Tarpey, 2007).…”