Term Frequency Exponent `\alpha` sets how the made-up words on a page are spread. The words are numbered by rank `r = 1, 2, \ldots, V`, with `V = 10 \times` Document Length, and each word of a page is drawn with

`P(r) \propto r^{-\alpha}`

so the word of rank 1 is `2^{\alpha}` times as likely as the word of rank 2, and `10^{\alpha}` times as likely as the word of rank 10. This is Zipf's law; `\alpha = 1` is the law as measured on real text. The choices run from 0.8 to 2.0.