  A robust, simple and fast procedure for the calculation of uncertainties in
relative static dielectric permittivity ($\varepsilon_s$) computed via
molecular dynamics (MD) is proposed. It arises as a direct application of well
founded statistical methods for auto-correlated variables. Also, in order to
deal with the lack of experimental data about $\varepsilon_s$ and relaxation
times ($\tau$) at different temperatures, a method for their prediction is
suggested. It requires one experimental value and at least two MD simulations.
In the case of relaxation times, a theoretical justification is provided.
