Comparison of radii for the benchmark validation sample derived by the binary pipeline, Gaia DR2, and computed from asteroseismic parameters (more details in Sect. 4.3). The colour-coding is by relative parallax uncertainty except in panel b, which is a copy of panel a, but colour-coded to indicate stars with less reliable seismic information (ν_max < 40; S. Sharma, priv. comm.). The more reliable part of the sample is used to calculate the bias and scatter as reported in panels a, c, and d. The colour scale in panel a is clipped for clarity, while panels b and c have a smaller range of σ_ϖ ∕ϖ because some Gaia DR2 values for radii were lacking.