inner vs. outer, or metal-rich vs. metal-poor) could be linked to different formation mechanisms. For example, state-of-the-art hydrodynamical simulations find that a significant fraction of the stellar haloes in the inner regions of Milky Way mass galaxies likely formed *in situ*, and are more akin (at least kinematically) to a puffed up disc component [@zolotov09; @font11; @pillepich15]. Thus, one would expect a stronger prograde rotation signal in the inner and/or metal-rich regions of the Milky Way stellar halo [@mccarthy12], and this theoretical scenario could account for the kinematic differences seen in the observations. However, as the detailed examination by [@fermani13b] shows, apparent kinematic signals depending on distance and/or metallicity can be wrongly inferred due to contamination in the halo star samples and/or systematic errors in the distance estimates to halo stars. Moreover, our observational inferences and comparisons with simulations should (but often do not) take into account the type of stars used to trace the halo. For example, commonly used tracers such as blue horizontal branch (BHB) and RR Lyrae (RRL) stars are biased towards old, metal-poor stellar populations, and this can affect the halo parameters we derive (see e.g. @xue11 [@janesh16]).

So far, our examination of the kinematics of 