The title of a research article has an almost impossible remit. As the freely available representative of the work, it needs to accurately capture what was achieved, differentiate it from other works, and, of course, attract the attention of the reader, who might be searching a journal’s contents list or the return from a database query.
Imagine you are explaining your research to a friend. You might say “I tested this factor” or “We examined that effect”. But when you later prepare a written version for a scientific journal, you would probably eliminate the “I” and “we” in favour of the passive voice, which, unfortunately, can sometimes present a challenge.