Grammatical complexity is a research area that focuses on studying the complexity of language structures and how they are formed. Researchers in this field may examine factors such as sentence length, word order, syntactic constructions, and the use of subordinate clauses to determine the level of complexity in a given language or text. The goal of studying grammatical complexity is to gain a better understanding of how languages are structured, how they evolve over time, and how they are processed and understood by speakers and listeners.