RR Lyrae PL relation in the K_s obtained i) via linear least-squares fits of the stars’ absolute magnitudes inferred from direct transformation of the TGAS parallaxes (upper panel); ii) via non-linear least-squares fits and the ABL method (middle panel); and iii) using the Bayesian approach (bottom panel). The slope of the fit is taken from Muraveva et al. (2015). Filled and empty circles represent fundamental-mode (RRab) and first overtone (RRc) stars, respectively. The bottom part of each panel shows the residuals from the best fit line.