of the importance of seeing: in 0.9arcsec seeing they measured a rotation velocity approximately half that measured for the same LBG in 0.5arcsec seeing. As discussed later, and illustrated in Figure \[fig:lbg\_rotationcurve\], we find that the reduction in measured rotation velocity in 0.5arcsec seeing is indeed significant. Another important effect not accounted for in Paper I is the variation of projected velocity across the finite width of the slit (0.76arcsec or 1.00arcsec). The influences of seeing; slit width; galaxy luminosity profile; galaxy orientation and inclination; the observational errors; and selection cuts all interact in a complex manner. In this paper we improve on our previous study by detailed modelling of these various effects and we investigate the sensitivity of our results to the assumptions made. We retain the formalism of the relation $V_{c7}=\alpha\sigma$ as the means of comparing theory and data. We employ a likelihood analysis, improving over the statistical analysis of Paper I. Throughout, we assume a standard, flat $\Lambda$CDM cosmology with $\Omega_\Lambda = 0.7$ and H$_0 = 70$[kms$^{-1}$Mpc$^{-1}$]{}.

Revised analysis
================

We follow the same principles as in our earlier analysis. The data analysed are the same seven rotation velocities, $V_r$, and 32 velocity widths, $\sigma$, summarised in 