  We assess the most macroscopic matter-wave experiments to date as to the
extent to which they probe the quantum-classical boundary by demonstrating
interference of heavy molecules and cold atomic ensembles. To this end, we
consider a rigorous Bayesian test protocol for a parametrized set of
hypothetical modifications of quantum theory, including well-studied
spontaneous collapse models, that destroy superpositions and reinstate
macrorealism. The range of modification parameters ruled out by the measurement
events quantifies the macroscopicity of a quantum experiment, while the shape
of the posterior distribution resulting from the Bayesian update reveals how
conclusive the data are at testing macrorealism. This protocol may serve as a
guide for the design of future matter-wave experiments ever closer to truly
macroscopic scales.
