Which type of source is considered less critical than primary sources in a literature review?

Secondary sources are considered less critical than primary sources in a literature review because they interpret, analyze, or summarize information from primary sources rather than presenting original research or findings. Primary sources, such as original research articles, experiments, or case studies, provide the foundational data and firsthand evidence that contributes to the advancement of knowledge in a field.

In contrast, secondary sources, while valuable for understanding the context and implications of primary research, do not offer direct evidence or findings. They may include reviews, meta-analyses, or articles that synthesize multiple studies but are one step removed from the original data. This distinction highlights their role in supporting but not replacing the importance of primary sources for establishing credibility and scientific rigor in research.