  Many deep wide-band wide-field radio interferometric surveys are being
designed to accurately measure intensities, spectral indices and polarization
properties of faint source populations. In this paper we compare various
wideband imaging methods to evaluate the accuracy to which intensities and
spectral indices of sources close to the confusion limit can be reconstructed.
We simulated a wideband single-pointing (C-array, L-Band (1-2GHz)) and
46-pointing mosaic(D-array, C-Band (4-8GHz)) JVLA observation using realistic
brightness distribution ranging from $1\mu$Jy to $100m$Jy and time-,frequency-,
polarization- and direction-dependent instrumental effects. The main results
from these comparisons are (a) errors in the reconstructed intensities and
spectral indices are larger for weaker sources even in the absence of simulated
noise, (b) errors are systematically lower for joint reconstruction methods
(such as MT-MFS) along with A-Projection for accurate primary beam correction,
and (c) use of MT-MFS for image reconstruction eliminates Clean-bias (which is
present otherwise). Auxiliary tests include solutions for deficiencies of data
partitioning methods (e.g. the use of masks to remove clean bias and hybrid
methods to remove sidelobes from sources left undeconvolved), the effect of
sources not at pixel centers and the consequences of various other numerical
approximations within software implementations. This paper also demonstrates
the level of detail at which such simulations must be done in order to reflect
reality, enable one to systematically identify specific reasons for every trend
that is observed and to estimate scientifically defensible imaging performance
metrics and the associated computational complexity of the algorithms/analysis
procedures.
