Heap's Law

[davidjackson]

  A confession - my excel formula was pointing to the wrong column, so the above are wrong. (The formula prediction was running against tokens found, no total types). So my above post was a waste of everybody's time, sorry.
Let me run the numbers afresh. I've also swapped the axis around.
The corrected graph for unique words (tokens) against all words (types) for the star section is this (spreadsheet with numbers also attached):
   

And for herbal section
   

Both with very similar numbers - the power B is increased by 0.01 in the second graph to give a slightly better fit.

Irrespective of the Heap's plotline, it's interesting to note that in the stars (which is mainly text) the rate of new tokens drops between 7000 and 11000 types of the corpus before picking up again. This could be representative of a repetitive subject being treated in this section of the text.

This doesn't happen in the herbal section, which has a much more constant rate of growth.