  This paper presents a probabilistic model validation methodology for
nonlinear systems in time-domain. The proposed formulation is simple,
intuitive, and accounts both deterministic and stochastic nonlinear systems
with parametric and nonparametric uncertainties. Instead of hard invalidation
methods available in the literature, a relaxed notion of validation in
probability is introduced. To guarantee provably correct inference, algorithm
for constructing probabilistically robust validation certificate is given along
with computational complexities. Several examples are worked out to illustrate
its use.
