Daniel is a sociolinguist specializing in syntactic variation with a focus on Southern United States English. He studies language variation, especially morphosyntactic variation in Southern English, through a blend of quantitative sociolinguistic and syntactic field methods. His theoretical analysis of the structure of the double modal construction of Southern English has been published in Lingua, and a discussion of microparametric variation in Southern English appears in Raffaella Zanuttini and Larry Horn's volume on Micro-parametric Variation in North America. Daniel’s quantitative sociolinguistic analyses of double modal acceptance and usage in Northeast Tennessee as well as in the Verilogue, Inc. corpus of doctor-patient consultations have been published in two articles in the University of Pennsylvania Working Papers in Linguistics.