“…Such a relationship is commonly referred to as a profile and may be represented by a simple linear, a multiple linear, a polynomial, or a nonlinear regression model. Simple linear profiles are mostly used in calibration applications and are widely studied in the literature for both Phases I and II monitoring; see, for example, Kang and Albin (2000), Kim et al (2003), Zhang et al (2009), Saghaei et al (2009), Mahmoud and Woodall (2004), Mahmoud et al (2010), Soleimani et al (2009), andHossienifard et al (2011). Besides, some authors including Mahmoud (2008), Jensen et al (2008), Amiri et al (2012), and Kazemzadeh et al (2010) considered more complicated models such as multiple linear and polynomial regression profiles.…”