  Analyzing Event-Triggered Control's (ETC) sampling behaviour is of paramount
importance, as it enables formal assessment of its sampling performance and
prediction of its sampling patterns. In this work, we formally analyze the
sampling behaviour of stochastic linear periodic ETC (PETC) systems by
computing bounds on associated metrics. Specifically, we consider functions
over sequences of state measurements and intersampling times that can be
expressed as average, multiplicative or cumulative rewards, and introduce their
expectations as metrics on PETC's sampling behaviour. We compute bounds on
these expectations, by constructing appropriate Interval Markov Chains equipped
with suitable reward structures, that abstract stochastic PETC's sampling
behaviour. Our results are illustrated on a numerical example, for which we
compute bounds on the expected average intersampling time and on the
probability of triggering with the maximum possible intersampling time in a
finite horizon.
