and concentration of haloes correlate with one another at different redshifts, Fig. \[Fig:CP\] shows the joint distribution of halo concentration and formation time at $z=0$ (left) and $z=3$ (right). We show both the distribution of the full set of haloes (contours) and the median concentration as a function of halo age for three narrow bins of halo mass (lines and errorbars). The jags in the contours in the $z=3$ panel are artificial being caused by the limited time resolution of the Millennium-WMAP7 simulation outputs at high redshift. At $z=0$ there is a clear trend of concentration increasing with formation redshift (as shown by the solid lines). On the other hand, at $z=3$ there is little variation of halo concentration with formation redshift which suggests that the assembly bias effect with concentration and halo age might be different. [@Xu:2018] also look at the correlation of halo bias with different secondary halo properties (including formation time and concentration). They show that this correlation changes dramatically with halo mass. Therefore, it is unsurprising that the evolution of the clustering signal with formation time and concentration of the halo is different (see also @Mao:2018 who studied the dependence of clustering on several halo secondary 