Moment ratios for absorbing-state phase transitions

We determine the first through fourth moments of the order parameter, and various ratios, for several one- and two-dimensional models with absorbing-state phase transitions. We perform a detailed analysis of the system-size dependence of these ratios and confirm that they are indeed universal for three models, the contact process, the A model, and the pair contact process, belonging to the directed percolation universality class. Our studies also yield a refined estimate for the critical point of the pair contact process. [S1063-651X(98)02410-6].