  We consider small-field models which invoke the usual framework for the
effective field theory, and large-field models which go beyond that. Present
and future possibilities for discriminating between the models are assessed, on
the assumption that the primordial curvature perturbation is generated during
inflation. With PLANCK data, the theoretical and observational uncertainties on
the spectral index will be comparable, providing useful discrimination between
small-field models. Further discrimination between models may come later
through the tensor fraction, the running of the spectral index and
non-gaussianity. The prediction for the trispectrum in a generic multi-field
inflation model is given for the first time.
