Machine derived contents note: Acknowledgements; Introduction; Part I. Methodology: 1. Preliminary considerations; 2. Data collection; 3. Methods of analysis; Part II. Linguistic Variation; 4. Verb forms; 5. Negation; 6. Relative pronouns; 7. Other nonstandard forms; Part III. Sociolinguistic Variation: 8. Social variation; 9. Stylistic variation; Conclusion; Appendix; Bibliography; Index of authors; General index