Fig. 5.
Scatter plot of the diffusivity estimated by BP and by MPA vs. the actual value of the diffusivity. Diffusion takes place in 3D, with displacements generated using κ∗ = 1. The actual value of the diffusivity κactual is computed from the actual trajectories and is subject to statistical fluctuations. The number of tracked particles is N = 100 (light gray) and N = 400 (dark gray) using 1,000 measurements. The BP predictions correspond to the maximum of the log-likelihood, as approximated by the Bethe free energy [6] discussed in the text. Note the strong underestimation of the MPA estimate, to be contrasted with the cloud of BP predictions centered around the correct value of κ∗.