To study the violation of the fluctuation-dissipation relation in glassy systems, particularly spin glasses, performed numerical simulations of macroscopic systems (i.e. large compared to their correlation lengths) described by the three-dimensional Edwards-Anderson model using supercomputers. In their simulations, the system is initially prepared at a high temperature, rapidly cooled to a temperature T = 0.64 T g below the glass temperature T g , and left to equilibrate for a very long time t w under a magnetic field H . Then, at a later time t + t w , two dynamical observables are probed, namely the response function χ χ ( t + t w , t w ) ≡ ≡ ∂ ∂ m ( t + t w ) ∂ ∂ H | H = 0 and the spin-temporal correlation function C ( t + t w , t w ) ≡ ≡ 1 V ∑ ∑ x ⟨ ⟨ S x ( t w ) S x ( t + t w ) ⟩ ⟩ | H = 0 where S x = ± ± 1 is the spin living on the node x of the cubic lattice of volume V , and m ( t ) ≡ ≡ 1 V ∑ ∑ x ⟨ ⟨ S x ( t ) ⟩ ⟩ is the magnetization density. The fluctuation-dissipation relation in this system can be written in terms of these observables as T χ χ ( t + t w , t w ) = 1 − − C ( t + t w , t w )