Seismic vs. TGAS parallaxes for the sample of 938 analysed red giant pulsators. The thick grey line is the bisector. Red lines: fits from an errors-in-variables model where the uncertainties on both parallaxes were taken into account; blue lines: fits obtained without taking any uncertainties into account. Solid lines are a fit using the linear model S_i = α + βϖ_i. Dashed lines are a fit using the model ϖ_i = κ + ρS_i. The curved dotted line is a fit using the model log D_i = 3 + α_l−(1 + β_l)log ϖ_i.