The interest in probabilistic real-time is increasing, in response to the lack of traditional static WCET analysis methods for applications running on complex systems, like multi/many-cores and COTS platforms. However, the probabilistic theory is still immature and, furthermore, it requires strong guarantees on the timing traces, in order to provide safe probabilistic-WCET estimations. These requirements can be verified with appropriate statistical tests, as described in this paper, and tested with synthetic and realistic sources, to assess their ability to detect unreliable results. In this work, we identified also the challenges and the problems of using statistical test based procedures for probabilistic real-time computin