  We analyse the proof of Bell's inequality and demonstrate that this
inequality is related to one particular model of probability theory, namely
Kolmogorov measure-theoretical axiomatics, 1933. We found a (numerical)
statistical correction to Bell's inequality. Such an additional term in the
right hand side of Bell's inequality can be considered as a probability
invariant of a quantum state. This is a measure of nonreproducibility of hidden
variables in different runs of experiments. Experiments to verify Bell's
inequality can be considered as just experiments to estimate this constant. It
seems that Bell's inequality could not be used as a crucial reason to deny
local realism. We consider deterministic as well as stochastic hidden variables
models.
