This article surveys some of the work in child language variation within the context of an historical perspective. An additional focus is on the possible contribution child language variation may make to language variation studies as a whole. For example, the concept of variable speaker, variable language, necessary to child variation when both developmental and dialectal variation are being examined, may be useful in a situation in which increased mobility throws the assumption of stability in the adult speaker into question.
Brown, K., & Roberts, J. L. (2006). Variation in Child Language. In Encyclopedia of Language & Linguistics (pp. 344–350). https://doi.org/http://dx.doi.org/10.1016/B0-08-044854-2/01495-4