A measure ν of a strange attractor which allows the presence of chaos to be distinguished from random noise. It is related to the capacity dimension D and information dimension σ, satisfying ν<=σ<=D. It satisfies ν<=D_KY, where D_KY is the Kaplan-Yorke dimension. As the cell size goes to zero, lim_(ϵ->0) ν->D_2, where D_2 is the correlation dimension.