  Interpretation of the \ion{Fe}{2}(UV)/\ion{Mg}{2} emission ratios from
quasars has a major cosmological motivation. Both Fe and Mg are produced by
short-lived massive stars. In addition, Fe is produced by accreting white dwarf
supernovae somewhat after star formation begins. Therefore, we expect that the
Fe/Mg ratio will gradually decrease with redshift. We have used data from the
Sloan Digital Sky Survey to explore the dependence of the
\ion{Fe}{2}(UV)/\ion{Mg}{2} ratio on redshift and on luminosity in the redshift
range of $0.75< z< 2.20$, and we have used predictions from our 830-level model
for the \ion{Fe}{2} atom in photoionization calculations to interpret our
findings.
  We have split the quasars into several groups based upon the value of their
\ion{Fe}{2}(UV)/\ion{Mg}{2} emission ratios, and then checked to see how the
fraction of quasars in each group varies with the increase of redshift. We next
examined the luminosity dependence of the \ion{Fe}{2}(UV)/\ion{Mg}{2} ratio,
and we found that beyond a threshold of \ion{Fe}{2}(UV)/\ion{Mg}{2} =~ 5, and
$M_{2500} < -25\rm mag$, the \ion{Fe}{2}(UV)/\ion{Mg}{2} ratio increases with
luminosity, as predicted by our model.
  We interpret our observed variation of the \ion{Fe}{2}(UV)/\ion{Mg}{2} ratio
with redshift as a result of the correlation of redshift with luminosity in a
magnitude limited quasar sample.
