In the hierarchy of evidence, where is expert opinion ranked?

In the hierarchy of evidence, expert opinion is typically ranked lowest due to its subjective nature. This ranking arises from the understanding that expert opinion is based on personal knowledge, experience, and interpretations, which may not be supported by rigorous empirical data. While expert opinions can provide valuable insights and context, they lack the systematic and objective evaluation found in higher forms of evidence, such as randomized controlled trials or systematic reviews. Therefore, relying solely on expert opinion can lead to biases and inconsistencies that empirical research seeks to mitigate. The lower ranking reflects the importance of evidence that is based on robust, reproducible research methodologies over expert interpretation alone.