This work reanalyzes published time series dispersion traces (Han et al., AIChE J. 1985:31:277-288) from step input tracer passages recorded at different locations along the length of a packed bed filled with monodisperse solid spheres. The intrinsic dispersivity and sample dependent dispersion are separated by imposing a heuristic model where coarse grained a-vial advection velocities vary in a plane perpendicular to the flow but not along the direction of flow. The derived intrinsic dispersivity agrees with the predicted value (Scheven et al., Phys Rev Lett. 2007:99:054502-1-054502-4). It serves as a bench mark for different implementations of simulations coupling Stokes flow and diffusion in random geometries, and for experimental tests of injection and packing methods. Conceptually, a well defined and fittable effective dispersivity is introduced in an analytical framework describing dispersion data obtained in non-ideal packed beds, where elution profiles cannot be fitted to the solution of the one dimensional advection diffusion equation. (C) 2009 American Institute of Chemical Engineers AIChE J, 56: 289-297, 2010