The Origin of the Non-Classical Character of the Quantum Probability Model

In [1] it is shown that a lack of knowledge about the measurements of a physical system gives rize to a non classical probability calculus for this physical system. It is also shown that the non classical probability calculus of quantum mechanics can be interpreted as being the result of a lack of knowledge about the measurements. Examples are given of macroscopical real systems that have a non classical probability calculus. Also an example is given of a macroscopical real system with a quantum probability model. More specifically a model for the spin of a spin 1/2 particle is constructed. Also an example is given of a macroscopical system having neither a classical nor a quantum probability model.