In
mathematics, a
moment is a specific quantitative measure, used in both
mechanics and
statistics, of the shape of a set of points. If the points represent
mass, then the zeroth moment is the total mass, the first moment divided by the total mass is the
center of mass, and the second moment is the
rotational inertia. If the points represent
probability density, then the zeroth moment is the total probability (i.e.
one), the first moment is the
mean, the second central moment is the
variance, the third moment is the
skewness, and the fourth moment (with normalization and shift) is the
kurtosis. The mathematical concept is closely related to the concept of
moment in
physics.