Relative abundance of Eu and K with respect to Mg (units in dex), obtained from the Hypatia Catalog Database (N. R. Hinkel et al. 2014). Red points show stars without detected planets; blue points show stars with detected planets. Marginal histograms illustrate the 1D ([K/Mg] and [Eu/Mg]) distributions for each group. Error bars correspond to reported measurement uncertainties.