Some groups or individuals are so trusted that citing their statements can be the deciding factor in getting people to agree with you. Some examples:
- The Centers for Disease Control
- The Congressional Budget Office
- The Census Bureau
- The Journal of the American Medical Association
The point that unites these groups listed above, and others like them, is that they are considered to be a leading authority in their specific field. When it comes to discovering information on any subject, going right to the leading authorities to find it out is always a sensible move.
If you are giving a presentation, going to a leading authority in the area you wish to discuss is very wise indeed. Sometimes in a presentation you will find that some of your listeners are skeptical and will challenge the statistics you mention. If you can mention that those statistics have come from a leading authority, and cite that they are up to date as well, then you will advance your case much further.
It has become common practice to begin sentences in presentations, essays and speeches with the phrase “Everybody knows that…” or “It goes without saying that…” when often this is very far from being the case.
This is a rhetorical device which can be used appropriately and inappropriately. In the first case, if it is something everyone does know, then it prevents you from having to go over well-worn explanations. In many other cases, however, it may be used because the speaker has not been able to source direct proof for an assertion and simply wants their audience to accept it. After all, if “everybody” knows something, not many people will happily be the one to disagree.
When it comes to backing your points up, it is best that you go to the experts.
The more evidence you can back up a statement with, the more confidence you can have in asserting it. Furthermore, the fact that the information comes from a trusted source means that you can immediately trump skeptical listeners who wish to make your presentation seem less informed than it is.