  By using straightforward frequency arguments we classify transformations of
probabilities which can be generated by transition from one preparation
procedure (context) to another. There are three classes of transformations
corresponding to statistical deviations of different magnitudes: (a)
trigonometric; (b) hyperbolic; (c) hyper-trigonometric. It is shown that not
only quantum preparation procedures can have trigonometric probabilistic
behaviour. We propose generalizations of ${\bf C}$-linear space probabilistic
calculus to describe non quantum (trigonometric and hyperbolic) probabilistic
transformations. We also analyse superposition principle in this framework.
