  We study the variation of word frequencies in Russian literary texts. Our
findings indicate that the standard deviation of a word's frequency across
texts depends on its average frequency according to a power law with exponent
$0.62,$ showing that the rarer words have a relatively larger degree of
frequency volatility (i.e., "burstiness").
  Several latent factors models have been estimated to investigate the
structure of the word frequency distribution. The dependence of a word's
frequency volatility on its average frequency can be explained by the asymmetry
in the distribution of latent factors.
