Event-by-event fluctuations in collective quantities

We discuss an event-by-event fluctuation analysis of particle production in heavy ion collisions. We compare different approaches to the evaluation of the event-by-event dynamical fluctuations in quantities defined on groups of particles, such quantities as mean transverse momentum, transverse momentum spectra slope, strength of anisotropic flow, etc. The direct computation of the dynamical fluctuations and the subevent method are discussed in more detail. We also show how the fluctuations in different variables can be related to each other. copyright 1999 The American Physical Society