  In this paper, we use an unprecedentedly large sample (158) of confirmed
strong lens systems for model selection, comparing five well studied
Friedmann-Robertson-Walker cosmologies: LCDM, wCDM (the standard model with a
variable dark-energy equation of state), the R_h=ct universe, the (empty) Milne
cosmology, and the classical Einstein-de Sitter (matter dominated) universe. We
first use these sources to optimize the parameters in the standard model and
show that they are consistent with Planck, though the quality of the best fit
is not satisfactory. We demonstrate that this is likely due to under-reported
errors, or to errors yet to be included in this kind of analysis. We suggest
that the missing dispersion may be due to scatter about a pure single
isothermal sphere (SIS) model that is often assumed for the mass distribution
in these lenses. We then use the Bayes information criterion, with the
inclusion of a suggested SIS dispersion, to calculate the relative likelihoods
and ranking of these models, showing that Milne and Einstein-de Sitter are
completely ruled out, while R_h=ct is preferred over LCDM/wCDM with a relative
probability of ~73% versus ~24%. The recently reported sample of new strong
lens candidates by the Dark Energy Survey, if confirmed, may be able to
demonstrate which of these two models is favoured over the other at a level
exceeding 3 sigma.
