How we change what others think, feel, believe and do
Credibility is, literally, the extent to which your audience believes you when you speak. It is about the trust they place in you, especially as being an expert in your topic.
Unlike simple trust, which is often given until a person is found untrustworthy, credibility often has to be earned, and people will look first to indicators such as achievements in education and employment, then to their first-hand experience of your presentation.
Initial credibility is that which you have before the presentation. This may be zero when people do not know you at all. It may also be very high if you are a known author, professor or personality who has achieved fame.
For those with low initial credibility, the task is to create credibility, which is where presented credibility is important and particularly derived credibility for real evidence.
For those with high initial credibility, the challenge is to live up to expectations, which may be artificially inflated, perhaps by your publicists or maybe by excessive admiration from your adoring audience!
Presented credibility is that which is presented to the audience before you speak. If there is a brief biography in event material then this may give them some indication of your achievements.
A powerful form of presented credibility is a glowing reference from other people who themselves have high credibility. This is often done when a known person introduces a person who is not known.
Things that add to presented credibility include:
Derived credibility comes from what you actually present. It comes from the quality of the material in your presentation, including the layout of your slides and the credibility of the facts you present. It comes from the words you use and how you say them. It also comes from how you dress and present yourself with clear authority.
A person with high initial credibility can lose significant credibility here if they are ill-prepared, which can happen to a famous person with an over-busy schedule. If your audience thinks you do not care enough about them, then they may feel betrayed and discount much of what you say.
A person with low initial credibility can do a lot here to build credibility with a clear, well-thought-out presentation and strong delivery. It does not have to be world-class as your audience likely does not expect this. But if you send them away with a good impression of both you and what you have said, your credibility will take a significant boost.
Terminal credibility is that which your audience takes away with them. Perhaps unfairly, if they admire you already, they may forgive you for a less than perfect display (although this is a dangerous game to play).
Equally unfairly, they may forget what a lesser-known speaker says, even though it is sound. This is one reason why it is important to make a solid and clear impact, not over-doing it nor presenting too much information. They will remember few things, so do remember to make your points clear and to give them a strong ending.