Social class has occupied a central place in the study of language variation since the rise of the discipline of sociolinguistics during the latter half of the twentieth century. Sociolinguists have correlated sociolinguistic variables such as postvocalic /r/ (e.g., car) with social factors such as class, sex, style, age, etc. A major finding of urban sociolinguistic work is that differences among social class dialects are quantitative and not qualitative. Generally speaking, the use of nonstandard forms increases the less formal the style and the lower one's social status, with men's scores higher than women's.