  The ratios of hydrogen Balmer emission line intensities in cataclysmic
variables are signatures of the physical processes that produce them. To
quantify those signatures relative to classifications of cataclysmic variable
types, we applied the multivariate statistical analysis methods of principal
components analysis and discriminant function analysis to the spectroscopic
emission data set of Williams (1983). The two analysis methods reveal two
different sources of variation in the ratios of the emission lines. The source
of variation seen in the principal components analysis was shown to be
correlated with the binary orbital period. The source of variation seen in the
discriminant function analysis was shown to be correlated with the equivalent
width of the H$\beta$ line. Comparison of the data scatterplot with
scatterplots of theoretical models shows that Balmer line emission from T CrB
systems is consistent with the photoionization of a surrounding nebula.
Otherwise, models that we considered do not reproduce the wide range of Balmer
decrements, including "inverted" decrements, seen in the data.
