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tokens: at the highest stellar masses ( M * > 10 10.5 M ⊙ ). The dashed vertical lines denote the 95 per cent completeness limits, determined at the upper redshift range ( z = 2). Representative error bounds for individual galaxies are shown on the left-hand panels, based on the median errors on the PSB sample. For the CANDELS sizes, data are taken from van der Wel et al. ( 2012 ), which include estimates for random and systematic errors from galfit . For the ground-based individual errors, we add in quadrature the scatter in δ R / R determined by the comparison with CANDELS (Section 3 ). The representative uncertainty on stellar masses is based on our Bayesian mass-fitting analysis described in Wild et al. ( 2016 ), as briefly outlined in Section 2.3 . The size–mass relations show the expected trends for star-forming and passive galaxies, consistent with previous studies (e.g. Daddi et al. 2005 ; Trujillo et al. 2006 ; van Dokkum et al. 2008 ; McLure et al. 2013 ; van der Wel et al. 2014 ). On average, passive galaxies appear significantly more compact than star-forming galaxies of equivalent stellar mass, but show a steeper size–mass relation, leading to convergence at the highest masses ( M * ∼ 10 11.5 M ⊙ ). Intriguingly, we find that PSB galaxies at this epoch are also extremely compact; they are comparable in size to the established passive galaxies, with evidence that they are smaller on average at high mass ( M * > 10 10.5 M ⊙ ). These trends are apparent with the large ground-based sample and with the smaller CANDELS sample. We performed a bootstrap analysis as a simple test of significance, randomly sampling the (ground-based) populations within each mass bin, with replacement. For the four bins above 10 10.5 M ⊙ , the fraction of the resampled populations in which the passive galaxies show mean sizes equal to (or smaller than) the mean of the PSB population are 0.07, 5 × 10 −5 , 1.2 × 10 −4 and 4 × 10 −5 (low-to-high mass, respectively). We note that the final bin contains 86 passive galaxies but only three PSBs, so the bootstrap comparison for this bin may be unreliable. Overall, assuming no systematic errors, we find evidence that massive PSB galaxies at z > 1 are significantly more compact, on average, than passive galaxies of comparable mass. Repeating the analysis using the median sizes produced very similar trends. The median analysis and further tests of robustness are presented in Appendix A . Our results are consistent with the findings of Yano et al. ( 2016 ), who also found evidence that high-redshift PSB galaxies are very compact. As an additional comparison, in Fig. 5 we display the distribution of for the three galaxy populations, measured for the redshift range 1 z 2 and stellar masses M * > 10 10.5 M ⊙ . Following Barro et al. ( 2013 ), we use this parameter to effectively remove the slope in the galaxy size/mass relation. Fitting a function of the form to the passive population, we find a best fit with α = 1.55, in very