Language change

Language change is systematic change over time in a community's sounds, grammatical patterns or meanings. It can be investigated by comparing historical records or repeated measurements, while separating change from differences in sampling, spelling and individual style. A text corpus supplies observations rather than a complete record of every speaker.

A 2007 study by Erez Lieberman and collaborators tracked 177 verbs irregular in Old English. In their dataset, 145 remained irregular at the Middle English stage and 98 at the modern endpoint. Their statistical model related the rate of verb regularization to usage frequency, with estimated half-life proportional to the square root of frequency.^[ref]

Under that fitted scaling, a 100-fold frequency increase predicts a tenfold half-life increase. This is an empirical relationship for the studied process and data, rather than a universal law for every kind of language change. The historical endpoint must not be mistaken for a fresh count of present-day usage.

Verb regularization is a form of language change in which an exceptional verb form is replaced by one following a productive grammatical pattern. For English past forms, this can mean adopting the -ed pattern rather than retaining an inherited alternative. Historical change in a speech community is distinct from a child's occasional application of a pattern to an irregular verb.

A quantitative study by Erez Lieberman and collaborators tracked irregular verbs across historical stages and identified help among verbs that became regular.^[ref] A hypothetical series with regular forms in 12 of 40 past-tense uses at one stage and 32 of 40 at another would show the regular variant's proportion rising from $0.3$ to $0.8$. Those counts alone would not establish the cause: recording practices, speaker composition and competing variants must also be checked. Regularization describes a pattern of inflection, not a judgment that the newer form is intrinsically better.