* Relevance: Does the source directly address the research question or support the chosen argument? A source's purpose clarifies whether it's genuinely useful or just tangentially related.
* Credibility: The purpose reveals the source's potential biases. A source aiming to persuade might present information selectively, whereas a purely informative source is likely to be more objective. Understanding the purpose helps assess the source's credibility and trustworthiness.
* Appropriate use: Knowing the purpose guides how the source can be used. A primary source offers firsthand accounts, while a secondary source provides analysis. A persuasive text might offer compelling arguments, but its evidence needs careful scrutiny. Understanding the purpose prevents misinterpreting or misrepresenting information.
* Completeness: Recognizing the limitations inherent in a source's purpose helps the researcher avoid relying solely on one type of source or perspective. It highlights the need for diverse sources offering different viewpoints and approaches.
In short, understanding a source's purpose is critical for selecting relevant, credible sources and integrating them effectively into a research report to build a strong, well-supported argument.