“…b E-mail: Pol.Tijskens@wur.nl statistical procedures have been developed and applied (non-linear mixed effect regression, non-linear indexed regression, quantile regression). Studies on longitudinal data (Hertog, 2002;Hertog et al, 2004Hertog et al, , 2007De Ketelaere et al, 2006;Schouten et al, 2004Schouten et al, , 2007Tijskens and Wilkinson, 1996;Tijskens et al, 1999Tijskens et al, , 2003Tijskens et al, , 2007Tijskens et al, , 2008Tijskens et al, , 2009bTijskens et al, , 2015aTijskens et al, , b, 2016Unuk et al, 2012) have proven that biological variation is not at all the result of a random process, but of distinct interactions of underlying kinetic processes. In other words, biological variation present in experimental data is strictly subject to deterministic rules.…”