  We compare numerical solutions to the full field equations to simplified
approaches based on implementing three collective coordinates for kink-antikink
interactions within the $\varphi^4$ and $\phi^6$ models in one time and one
space dimensions. We particularly pursue the question whether the collective
coordinate approximation substantiates the conjecture that vibrational modes
are important for resonance structures to occur in kink-antikink scattering.
