  The standard deviation (SD) quantifies the spread of the observed values on a
measurement of an observable. In this paper, we study the distribution of SD
among the different components of a superposition state. It is found that the
SD of an observable on a superposition state can be well bounded by the SDs of
the superposed states. We also show that the bounds also serve as good bounds
on coherence of a superposition state. As a further generalization, we give an
alternative definition of incompatibility of two observables subject to a given
state and show how the incompatibility subject to a superposition state is
distributed.
