A computer-implemented method (100) for refining the risk α that an uncertain quantity x in an industrial process (1a) and / or
electrical network (1b) will exceed a given threshold value x, the method comprising the steps of: • providing (110) an initial desired value a* of the risk α; • providing (120) a prediction model (2) that is configured to predict, from values x t ,x t-1 ,..., x t-k of the quantity x, future values x t+1 ,..., x t+1 of this quantity x; • providing (130) a history x # of measured past values x t , x t-1 ,..., x t-k of the quantity x; • determining (140), for this history x # , differences between values x t , x t-1 ,..., x t-k predicted by the prediction model and the measured past values x t , x t-1 ,..., x t-k as residuals (3); • determining (150) an estimated probability density function (4) of these residuals (3); • determining (160), based at least in part on the history x # , and / or on the residuals (3), a
confidence set 2) to which the estimated probability density function (4) belongs, said
confidence set D comprising probability density functions that would be equally plausible given the history x # and / or the residuals (3); and • determining (170), based at least in part on the dimension of the
confidence set D, a new risk α' such that, if the risk a that x exceeds x is less than α', it is guaranteed that this risk α will not exceed the initial desired value α* even if the residuals should behave according to any one of the probability density functions in the confidence set D instead of the estimated probability density function (4).