  Recent observations suggest that the spectral index of the primordial
perturbations is very close to unity, as expected in models of slow roll
inflation. It is still possible for such models to produce spectra which are
scale dependent. We present a formula for the spectrum produced by an arbitrary
inflaton potential (within the context of slow roll models); this formula
explicitly illustrates and accounts for the possiblity of scale dependence. A
class of examples are studied and comparisons made with the standard slow roll
formula.
