Moderators can apply post notices to answers that are substantially lacking in either explanation:
We're looking for long answers that provide some explanation and context. Don't just give a one-line answer; explain why your answer is right, ideally with citations. Answers that don't include explanations may be removed.
This post does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.
I have occasionally used the former; I have never used the latter, since lack of citation is not a criterion for deletion on the site I moderate. At first, I expected that a "needs improvement" notice would attract more downvotes to an answer than usual—by the strength of authority of the notice, or a sense of having received permission, for example. After some observation, I didn't see any particular evidence that was the case, and considered that diffusion of responsibility might also influence readers not to vote where otherwise they might be inclined to downvote (particularly when a good alternative choice, i.e., an accepted or more highly-voted answer, is present).
Currently we have only 5 of 3,130 non-deleted answers noticed in this manner on Engineering; this is not much of a sample for analysing something as complex as voting patterns and motivations. I know that other sites are larger and some use these notices more frequently, so perhaps there's enough data network-wide to have a shot at answering this:
When I am considering adding a post notice to an answer, how can I expect the notice to influence voting?