Variation in noun and pronoun frequencies in a sociohistorical corpus of English.

Many corpus linguists make the tacit assumption that part-of-speech frequencies remain constant during the period of observation. In this article, we will consider two related issues: (1) the reliability of part-of-speech tagging in a diachronic corpus and (2) shifts in tag ratios over time. The purpose is both to serve the users of the corpus by making them aware of potential problems, and to obtain linguistically interesting results. We use noun and pronoun ratios as diagnostics indicative of opposing stylistic tendencies, but we are also interested in testing whether any observed variation in the ratios could be accounted for in sociolinguistic terms. The material for our study is provided by the Parsed Corpus of Early English Correspondence (PCEEC), which consists of 2.2 million running words covering the period 1415-1681. The part-of-speech tagging of the PCEEC has its problems, which we test by reannotating the corpus according to our own principles and comparing the two annotations. While there are quite a few changes, the mean percentage of change is very small for both nouns and pronouns. As for variation over time, the mean frequency of nouns declines somewhat, while the mean frequency of pronouns fluctuates with no clear diachronic trend. However, women consistently use more pronouns than men, while men use more nouns than women. More fine-grained distinctions are needed to uncover further regularities and possible reasons for this variation.