Starting a sentence with "it" is acceptable in APA, but doing so may make sentences needlessly wordy and take the emphasis off of the subject.
“It was found that 25% of… (Smith & Taylor, 2016)” is a grammatically acceptable way to begin a sentence.
Although grammatically acceptable, beginning the sentence with "it" instead of naming the subject can also lead to passive voice, in which the verb ("was") precedes the subject/actor (the researchers, Smith and Taylor).
APA recommends choosing voice carefully, and this often means opting for active voice, in which the subject/actor of the sentence precedes the verb, over passive voice in the interest of clarity..
Beginning the sentence by writing:
“Smith and Taylor (2016) found that…” or “Researchers found that… (Smith & Taylor, 2016)”
is a more concise and precise way of presenting the same information due to the use of active voice construction.
If you decide to begin a sentence with "It," we suggest doing so sparingly and for specific reasons, such as to take the emphasis off of the subject, to avoid overuse of the subject (repetition), or to vary sentence structure (e.g., not starting every sentence with an author’s name or with “Researchers…”).
Outside of the specific reasons for using "it" listed in the previous paragraph, its use is often a wasted opportunity to be more concise and accurate in your writing. Avoid ambiguity, be more concise, and use the active voice by replacing the word "it" with the subject itself.
For more information how to avoid beginning sentences with "it" (also known as expletive constructions), check out the following resources:
When using "it," avoid being vague or ambiguous by alternatively referring clearly to a specific noun in the sentence.
Incorrect example: Even though the demographic questionnaire is often used in tandem with the survey, I did not have the participants complete it in this study. (Does the "it" refer to the demographic questionnaire or the survey?)
Correct example: Knowles (1973) developed the theory of andragogy, and it is often used as a foundational study in research concerning adult learners. (The "it" in this sentence can only refer the specific noun in the previous clause, "the theory.")
Incorrect example: If a participant skips answering a question in the survey, I will code it as incomplete. (What does the "it" refer to, the question that was not answered or the whole survey?)
Correct example: If you download the Abstract Guidelines document, you can refer to it while drafting the abstract for your study. (Because there is only one specific noun, the "document," in the first clause, the use of "it" in the second clause to refer to the document is clear and not ambiguous.)