  The complex structure of the light curves of Swift GRBs has made their
interpretation and that of the blast wave caused by the burst, more difficult
than in the pre-Swift era. We aim to constrain the blast wave parameters:
electron energy distribution, p, density profile of the circumburst medium, k,
and the continued energy injection index, q. We do so by comparing the observed
multi-wavelength light curves and X-ray spectra of a Swift sample to the
predictions of the blast wave model.
  We can successfully interpret all of the bursts in our sample of 10, except
two, within the framework of the blast wave model, and we can estimate with
confidence the electron energy distribution index for 6 of the sample.
Furthermore we identify jet breaks in half of the bursts. A statistical
analysis of the distribution of p reveals that, even in the most conservative
case of least scatter, the values are not consistent with a single, universal
value. The values of k suggest that the circumburst density profiles are not
drawn from only one of the constant density or wind-like media populations.
