parameters. Full details of the <span style="font-variant:small-caps;">GALFIT</span> measurement of structural parameters within CANDELS are given in van der Wel et al. (2012).

![image](size2_z12.pdf){width="0.45\linewidth"} ![image](size1_z12.pdf){width="0.45\linewidth"} ![image](size2hst_z12.pdf){width="0.45\linewidth"} ![image](size1hst_z12.pdf){width="0.45\linewidth"}

![We compare the distribution of $\Sigma_{1.5}$ values for the three galaxy populations in the redshift range $1<z<2$, with stellar masses M$_{\ast}> 10^{10.5} ~$M$_{\sun}$. This parameter ($\Sigma_{1.5} \equiv$M$_{\ast}/R_e^{1.5}$), defined by Barro et al. (2013), effectively removes the slope of the galaxy mass/size relation; high values of $\Sigma_{1.5}$ correspond to galaxies that are compact for their stellar mass. A KS test rejects the null hypothesis that passive galaxies and PSBs are drawn from the same underlying distribution in $\Sigma_{1.5}$, with a significance of $>99.99\%$.[]{data-label="fig:sigma15"}](sigma15.pdf){width="0.9\linewidth"}

![image](size1_z115.pdf){width="0.45\linewidth"} ![image](size1_z152.pdf){width="0.45\linewidth"}

Ground-based measurements of size and Sérsic index {#sec:sizesersic}
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We determined structural parameters for the $K$-band galaxy sample using the <span style="font-variant:small-caps;">GALAPAGOS</span> software (Barden et al. 2012). The package allows the automated use of <span style="font-variant:small-caps;">GALFIT</span> (Peng et al. 2002) to fit Sérsic light profiles (Sérsic 1968) to all galaxies in the UDS, parameterized with a Sérsic index, $n$, and effective radius, $R_e$, measured along the semi-major axis. We acknowledge that many high-redshift galaxies are described by more complex morphologies (see Bruce et al. 2014), but single Sérsic fits provide 