The reliance on a differential quantity, ⁠ Δ z / Δ t ⁠, brings more information and is appealing for computation: It can minimize many common issues and systematic effects. Analyses of supernovae and baryon acoustic oscillations (BAO) are based on integrals of the Hubble parameter, whereas ⁠ Δ z / Δ t ⁠ measures it directly. For these reasons, this method has been widely used to examine the accelerated cosmic expansion and study properties of dark energy.