Measuring Fermi velocities with ARPES in narrow band systems: The case of layered cobaltates

► Fermi velocities are measured in various cobaltates compounds, thanks to Angle-Resolved Photoemission. ► The dependence of this value on the method of analysis is emphasized and attributed to a k-dependence of the self-energy. ► These results should be useful for extracting correct Fermi velocities in any strongly correlated materials, with small Fermi velocities.