kroch constant rate hypothesis content length 1953 kroch 1989 argues syntactic change progresses rate contexts using ellegard 1953 data auxiliary challenge notion changes diffuse obviously important claim kroch methodology matching theoretical syntax highlevel stats also seems important advance historical linguistics however ogura 1993 direct challenge kroch reusing ellegard data statistical method claiming data actually shows opposite kroch claims e change auxiliary use differs rate contexts working auxiliary within variationist model judging right argument stats literate person help reply kroch aware anthony kroch 1989 reflexes grammar patterns language change language variation change 1 pp 199244 mieko ogura 1993 development periphrastic english diachronica x 1 pp 5185 jonathan hope j r hope leeds uk ac school english university leeds uk