Before revision:  amounts to the effective size of its event space, and can be quantified using the R\'enyi family of indices (also known as Hill numbers in ecology or Hannah-Kay indices in economics), which are indexed by an elasticity parameter q \geq 0. Importantly, under these indices, the heterogeneity of a composite system (the \gamma-heterogeneity) is decomposable into heterogeneity arising from variation within and between component subsystems (the \alpha- and \beta -heterogeneities , respectively).
After revision:  is the effective size of its event space, and can be quantified using the R\'enyi family of indices (also known as Hill numbers in ecology or Hannah-Kay indices in economics), which are indexed by an elasticity parameter q \geq 0. Importantly, under these indices, the heterogeneity of a composite system (the \gamma-heterogeneity) is decomposable into heterogeneity arising from variation within and between component subsystems (the \alpha- and \beta -heterogeneities , respectively).