Title: Stochastic Models for Analysing the Stability of Oscillators Abstract: In many applications, mathematical modelling yields time-dependent systems of ordinary differential equations (ODEs) or differential algebraic equations (DAEs). We focus on oscillators, i.e., dynamical systems including periodic solutions. The stability of the periodic limit cycles represents an important information. To analyse the stability properties, we consider perturbations in the initial values of the solution or in the right-hand side of the system. Furthermore, the sensitivity of the solution with respect to technical parameters of the dynamical system has often to be determined. We construct stochastic models to achieve global information on stability and sensitivity of oscillators. Monte Carlo methods are feasible to compute results of the models like expected values or variances of the stochastic processes. Alternatively, we apply the strategy of the generalised polynomial chaos to determine according approximations. Numerical simulations for systems of ODEs and DAEs are presented using the stochastic models and the methods based on polynomial chaos.