To establish credibility in a speech, provide fact-based evidence for claims, provide evidence of expertise and knowledge, and connect with the audience. The appropriate way to establish credibility in a speech often depends on whether or not the audience is skeptical of the speaker's credibility to begin with.
To establish credibility in a speech:
Provide fact-based evidence
Illustrate all points or assertions with facts and figures from credible sources. Statistics, for example, should come from authoritative governments or entities.
Provide evidence of expertise
Establish the speaker's expertise with details about his or her education or experience. The number of years worked in an industry or the type of degree that is held might be relevant.
Connect with the audience
Find common ground with the audience through shared experiences or perspectives. Telling stories or anecdotes is one viable option.