We have investigated the structural and electronic properties of amorphous TiO2 using molecular dynamics (MD) simulations based on ab initio density functional theory, a numerically efficient density-functional-based tight-binding approach and classical many-body potentials. The lower level approximations are successively validated by the higher level ones through comparison of the calculated structural and electronic properties. The classical results reproduce all relevant structural features of a-TiO2 as obtained by quantum-mechanical simulation and reproduce the experimentally observed reduced radial distribution function. This gives convincing justification for the use of classical MD in the simulation of ion beam sputtering synthesis of large-area amorphous thin films. Cross-correlation of electronic data with the statistics of disorder-induced under- and over-coordination is derived as a basis for evaluating the optical quality of thin-film coatings