Purpose
The fourth step of DAPPR is to look at a source's purpose. The goal here is to understand why the information you're looking at was published. For college-level research, the purpose of a source should be to promote research or to provide factual information. If you are looking at a source whose purpose seems to be to sell something, or to entertain, this is probably not a good source for college-level research.
Tip: The purpose of the source is not the thesis or description of the article/book/video/etc. Instead, think about what the author was trying to do by publishing this information. Did they want to provide factual information? Were they sharing research that might lead to more knowledge and research on this topic? Were they trying to sell something or convince you of a certain idea?
Bias Part 1
This video explains how important it is to really dig into the purpose of a source to see if they have any biases, and why failing to account for purpose can lead to you using less reliable sources than you might have intended.
Bias Part 2
In addition to bias within an organization like we saw in the video to the left, it's also very important to consider whether a source's information is rooted in facts, or whether this source wants to convert you to a specific viewpoint. College-level research should not use biased language or be based in opinion, but should try to stick to facts and data. Watch the following video to see an example.