Are low-frequency complex prepositions grammaticalized?

Using extensive corpus data, this paper investigates whether low-frequency complex prepositions (e.g. by dint of, in conformity with) can be interpreted as units of language structure even though they cannot have undergone the processes typical of more frequent grammaticalizing constructions. I critically evaluate previous treatments of frequency and discuss alternative modes of interpreting corpus data, e.g. by drawing a distinction between conceptual and absolute frequency as reflections of the cognitive representation of linguistic items. I also suggest that formal properties of grammaticalizing constructions may play an important role and that “grammaticalization by analogy” may account for the establishment of low-frequency units of language. Finally, the paper offers a detailed discussion of the methodological issues involved in using corpus data to study low-frequency phenomena.