OCLRE Rules of Evidence Practice Test

The key idea is that an expert can reveal the data that supports their opinion during testimony to show how the conclusion was reached. They may do this by answering a hypothetical question that assumes the data and walks through the reasoning, or by responding to other questions that elicit the data or the method used. This keeps the explanation transparent so the judge and jury can evaluate reliability and relevance of the opinion.

The other options are too restrictive: the data isn’t limited to a written report, it isn’t restricted to after the jury asks for it, and it isn’t prohibited from being discussed at all. In practice, experts commonly disclose underlying data on the stand when asked or when a hypothetical question demonstrates how the data supports the opinion.