Software

Examples of scripts computing ARF (average reduced frequency) in a language corpus according to

P. Savický, J. Hlaváčová. Measures of Word Commonness. Journal of Quantitative Linguistics, Vol. 9, No. 3, 215-231, 2003.

may be found in word_commonness-0-1.tar.gz. For other related measures, see

S. Th. Gries. Dispersions and adjusted frequencies in corpora. International Journal of Corpus Linguistics 13(4), 403-437, 2008.

and other papers on dispersion of word occurences at publications of Stefan Th. Gries.