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Communication 104: Evaluating Sources

Guide to Evaluating Sources

From the many volumes and electronic resources you have access to through the Harvard library system to the many resources available on the Web, finding information has never been easier. But at times, the sheer volume of information available to you can be overwhelming: How will you know which sources to rely on? How will you decide which sources are appropriate for a particular assignment? How can you determine if the data on a Web site is trustworthy? 
Although the most useful sources for a given assignment will depend on the assignment itself, as well as on the kinds of sources generally relied upon in your field of study, there are some universal rules that will help you decide whether to use a source. Once you determine whether a source is worth looking at, you'll still need to figure out what you will do with it in your paperhow to avoid plagiarism, and how to cite the information and ideas you draw from it. When you write for an academic audience, you are responsible for making sure that any information you provide and any ideas you cite come from sources that are both reliable and appropriate for your assignment. The most reliable sources are those that have been vetted by scholars in the field—articles published in peer-reviewed journals and books published by academic publishers.

No matter what you're working on, keep in mind that not all sources are appropriate for your project; just because someone has written something down doesn't mean it is worthy of discussion. Before you decide to rely on a source, you should evaluate the source and decide whether it is appropriate to use in your paper. You should always determine the qualifications of the author, the purpose of the source (that is, in what context is was created), the scope of the source (what it covers and in what depth), and, where relevant, the currency of the source.

Process for Avoiding Deception

A Process for Avoiding Deception

  1. Keep an open mind. Most of us have biases, and we can easily fool ourselves if we don’t make a conscious effort to keep our minds open to new information. Psychologists have shown over and over again that humans naturally tend to accept any information that supports what they already believe, even if the information isn’t very reliable. And humans also naturally tend to reject information that conflicts with those beliefs, even if the information is solid. These predilections are powerful. Unless we make an active effort to listen to all sides we can become trapped into believing something that isn’t so, and won’t even know it.
  2. Ask the right questions. Don’t accept claims at face value; test them by asking a few questions. Who is speaking, and where are they getting their information? How can I validate what they’re saying? What facts would prove this claim wrong? Does the evidence presented really back up what’s being said? If an ad says a product is “better,” for instance, what does that mean? Better than what?
  3. Cross-check. Don't rely on one source or one study, but look to see what others say. When two or three reliable sources independently report the same facts or conclusions, you can be more confident of them. But when two independent sources contradict each other, you know you need to dig more deeply to discover who’s right.
  4. Consider the source. Not all sources are equal. As any CSI viewer knows, sometimes physical evidence is a better source than an eyewitness, whose memory can play tricks. And an eyewitness is more credible than somebody telling a story they heard from somebody else. By the same token, an Internet website that offers primary source material is more trustworthy than one that publishes information gained second- or third-hand. For example, official vote totals posted by a county clerk or state election board are more authoritative than election returns reported by a political blog or even a newspaper, which can be out of date or mistaken.
  5. Weigh the evidence. Know the difference between random anecdotes and real scientific data from controlled studies. Know how to avoid common errors of reasoning, such as assuming that one thing causes another simply because the two happen one after the other. Does a rooster’s crowing cause the sun to rise? Only a rooster would think so.



Evaluating Information Helpsheet