Absolute yttrium abundance versus absolute magnesium abundance together with a linear fit. Symbols are the same as in Fig. 5. Different line styles and colors indicate different fitting techniques. LS denotes a least squares fitting without any weights. The slope given in each panel is calculated with this fitting technique. WLS indicates a weighted least squares fit, ODR stands for an orthogonal distance regression, and Bagging for a bootstrapping aggregation. Light gray lines indicate different slopes that are involved in the bootstrapping algorithm. The line in the lower right panel indicates a 1:1 correlation without performing a fit.