The global response to weak time periodic forces of an array of noisy, coupled nonlinear systems might show a nonmonotonic dependence on the number of units in the array. This effect has been termed system size stochastic resonance by other authors. In this paper, we focus on a collective variable of a finite array of one-dimensional globally coupled bistable elements. We analyze the possible nonmonotonic dependence on the system size of its power spectral amplification and its signal-to-noise ratio.