Using Facts and Statistics in a Speech

In Aristotle's Rhetoric, one of the three proofs that he discussed in order to appeal to a specific audience was logos. Logos is an approach using facts and objective analysis to appeal to the audience's sense of logic.
Facts, I believe, are good in most any kind of speech that is meant to inform or persuade an audience. Of course, when gathering facts it is of vital importance to check and double check your sources and to use credible sources. Including facts in your speech can provide support for your topic by offering a broader view of the topic being discussed beyond the opinions of the speaker and can also help to establish your credibility as a speaker.
Using statistics can a provide helpful numerical data or information in your speech. The data needs to be accurate and from credible sources. The drawback here is that statistical data can be used inappropriately to skew the facts and/or mislead an audience. However when used properly, statistics can serve as beneficial supporting material for any speech that is intended to educate or persuade the audience.
Facts and statistics may not be as useful in a speech meant to entertain where one might, for instance, opt to use examples of narrative instead.  They can, however, be key in the success of a speech that is based in logic and reason.