When is it appropriate to use a biased opinion in research paper?

In academic research, it is generally not appropriate to use biased opinions as a basis for arguments or conclusions. The goal of research is to present factual information and analysis based on evidence, rather than promoting personal viewpoints or biases. Using biased opinions can undermine the credibility and objectivity of the research and may lead to inaccurate or misleading conclusions. Instead, researchers should strive to be impartial, objective, and evidence-based in their approach to research.