“…gender and age) is referred to as measurement invariance and can be examined with different statistical methods (Mellenbergh, 1989;Meredith, 1993;Millsap, 2012). Cross-sectional personality development studies that test for measurement invariance across age (Allemand, Zimprich, & Hendriks, 2008;Allemand, Zimprich, & Hertzog, 2007;Brandt et al, 2018;Nye, Allemand, Gosling, Potter, & Roberts, 2016;Olaru et al, 2018) usually examine measurement invariance across age groups by artificially categorizing age in an arbitrary number of groups after separating them based on equally arbitrary thresholds, even though age is continuous in nature. This approach and the associated decisions concerning number of groups, for example, will inevitably influence the results and can therefore provide us with a distorted picture of personality development (Hildebrandt, Lüdtke, Robitzsch, Sommer, & Wilhelm, 2016;Hildebrandt, Wilhelm, & Robitzsch, 2009;MacCallum, Zhang, Preacher, & Rucker, 2002).…”