@staticmethod
def _get_normalised_term(pval, pmax, pmin):
    """
        Normalisation of a variable between its minimum and maximum using:
        2.0 * ((p - p_min) / (p_max - p_min)) - 1
        N.B. This is given as 0.5 * (...) - 1 in the paper, but the Electronic
        Supplement implements it as 2.0 * (...) - 1
        """
    return 2.0 * ((pval - pmin) / (pmax - pmin)) - 1
