Perturbed Power-law parameters from WMAP7

We present a perturbative approach for studying inflation models with soft departures from scale free spectra of the power law model. In the perturbed power law (PPL) approach one obtains at the leading order both the scalar and tensor power spectra with the running of their spectral indices, in contrast to the widely used slow roll expansion. The PPL spectrum is confronted data and we show that the PPL parameters are well estimated from WMAP-7 data.