  The large in-plane anisotropy of the resistivity is a hallmark of the nematic
state of the iron pnictides. Solving the Boltzmann transport equation, we show
that the prominent doping dependence as well as the large values of the
anisotropy can be well explained by momentum-dependent spin-fluctuation
scattering without assuming anisotropic impurity states. Due to the
forward-scattering corrections, the hot spots contribute to the resistive
anisotropy even in the case of strong spin fluctuations, which makes large
values of the anisotropy possible. The ellipticity of the electron pockets
plays an important role in explaining the dominance of positive values of the
anisotropy, i.e., larger resistivity in the direction with weaker spin
fluctuations, throughout the doping range.
