  Dealing with quadratic payments, marginal probability is usually considered
ideally constant, maybe for the sake of initial simplicity. Considering the
voting scenario depicted in "Quadratic Payments: A Primer" by Vitalik Buterin,
firstly its math foundations are made explicit. Developing a simple referendum
model, more realistic outcome probability and marginal probability qualitative
shapes are introduced. Enforcing seemingly reasonable assumptions, quadratic
payments are then generalized to take into account these new functions shapes,
and the way they are still quadratic is discussed. Closing remarks underline
the emerging of trade-off constraints not existing in ideal case.
