relative_frequency
has definitions from the field of statistics


1 
[ noun ] (statistics) the ratio of the number of observations in a statistical category to the total number of observations
Synonyms Used in print (A.L. Kroeber, "Semantic Contribution of Lexicostatistic...)Thomas also presents a simple equation for deriving an index of persistence , which weights not_only the number of stems ( ' roots ' ) per meaning , but their relative_frequency . As to relative_frequencies of competing roots ( 7  1 vs. 4  4 , etc_. ) , Thomas with his ' weighting ' seems to be the first to have considered the significance this might have . 
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