Research has shown that “80% of statements made in speeches about research can’t be backed up”. Including that statement, which I just made up.
Therein lies the problem. Simply saying “Research has shown..” or “It’s been proved that..” won’t work any more. Anyone in your audience can tap into their mobile phone to find out whether your statement has any validity. Of course, the Internet is not infallible, and different views exist, especially among researchers. However, if you give details of the study you’re referencing, at least people can check that you didn’t just make it up. It’s much better to say “A study at MIT in 1982 with a thousand responses indicated that….”
It’s easy to quote references, and if you can’t find any, drop the statement. Even more shaky ground is trodden by speakers who use a story as “proof” of something. A story is a usually a single example of something happening. It may be a great analogy, but it isn’t a general proof. As the saying goes – “The plural of anecdote is not data”.
So backup your statements with references, and make sure your speech is web-proof.