Abstract
Based on the connection between a sublattice dilute q-state Potts model (SDQPM) and a correlated percolation model, we define a nonpercolating geometrical factor gf and a percolating geometrical factor gp, which depend only on q and geometrical properties of the system. The thermal properties of the SDQPM may be derived simply from gf and gp. The theory is confirmed by an exact calculation for one-dimensional SDQPM and may be extended to other interacting systems.