Fluctuations in finite critical and turbulent systems

We show that hyperscaling and finite-size scaling imply that the probabilit y distribution of the order parameter in finite-size critical systems exhib it data collapse. We consider the examples of equilibrium critical systems, and a statistical model of ecology. We propose an explanation for recent o bservations that the probability distribution of turbulent power fluctuatio ns in closed Rows is the same as that of the harmonic 2DXY model.