Conventions of Academic Writing

According to a study by Robert Connor and Andrea Lunsford, 91.5 percent of grammar mistakes come from the following list of errors.  Very few writers make all of these mistakes, so if you can identify just one or two of your weaknesses and work to improve them, you can significantly cut the number of mistakes in your work.

The twenty most common grammar errors are (in order of frequency in which they occur):

1. No comma after introductory phrases
2. Vague pronoun references
3. No comma in compound sentence
4. Wrong word
5. No comma around non-restrictive clauses
6. Wrong/missing inflected endings
7. Wrong/missing preposition
8. Comma Splices
9. Possessive apostrophe error
10. Tense shift
11. Unnecessary shift in person
12. Sentence fragment
13. Wrong tense or verb form
14. Subject-verb agreement
15. Lack of comma in a series
16. Pronoun agreement error
17. Unnecessary commas with restrictive clauses
18. Run on, fused sentence
19. Dangling, misplaced modifier
20. Its/it's error

Dartmouth College provides a brief explanation of each of these errors on their Writing Program website.  For an even more extensive discussion of grammar, mechanics, and punctuation conventions, you should familiarize yourself with the Purdue OWL's General Writing sub-sections.