We consider properties of the measurement intensity $rho$ of a random variable for which the probability density function represented by the corresponding Wigner function attains negative values on a part of the domain. We consider a simple economic
interpretation of this problem. This model is used to present the applicability of the method to the analysis of the negative probability on markets where there are anomalies in the law of supply and demand (e.g. Giffens goods). It turns out that the new conditions to optimize the intensity $rho$ require a new strategy. We propose a strategy (so-called $grave{a}$ rebours strategy) based on the fixed point method and explore its effectiveness.
