Final answer:
The usefulness of information in a source for a given purpose is known as reliability, which is determined by how well it serves the researcher's or writer's specific needs, taking into account bias and the author's purpose.
Step-by-step explanation:
The usefulness of information in a source for a given purpose is also known as reliability. Reliability refers to the consistency and dependability of information within the source to serve the researcher's or writer's specific needs. When evaluating a source for reliability, one must consider the author's purpose, whether the information is factual or opinionated, and the presence of any biases.
It's not solely about whether the information is truthful or misleading; a source becomes valuable based on its ability to fulfill the intended purpose. Biased material might be useful in analyzing how certain narratives are constructed, while even accurate sources can be misused if they do not align with the researcher’s objectives.