A multivariate Berry--Esseen theorem for time-dependent expanding dynamical systems

We adapt Stein's method to obtain Berry--Esseen type error bounds in the multivariate central limit theorem for non-stationary processes generated by time-dependent compositions of uniformly expanding dynamical systems. In a particular case of random dynamical systems with a strongly mixing base transformation, we derive an error estimate of order $O(N^{-1/2})$ in the quenched multivariate CLT, provided that the covariance matrix "grows linearly" with the number of summands $N$. The error in the normal approximation is estimated for the class of all convex sets.