Identify the error in this sentence: The research, including dozens of interviews conducted over the past two years.

The sentence in question is a fragment because it lacks a main clause that provides a complete thought. A complete sentence generally needs both a subject and a verb, and it should express a complete idea. In this case, "The research, including dozens of interviews conducted over the past two years" does not convey a complete idea and leaves the reader expecting more information.

To correct this fragment, you would need to provide additional information that completes the thought, such as "The research, including dozens of interviews conducted over the past two years, reveals significant findings." This revision turns the fragment into a full sentence, resolving the issue.