This handout will provide a broad overview of gathering and using evidence. It will help you decide what counts as evidence, put evidence to work in your writing, and determine whether you have enough evidence. It will also offer links to additional resources.
Many papers that you write in college will require you to make an argument; this means that you must take a position on the subject you are discussing and support that position with evidence. It’s important that you use the right kind of evidence, that you use it effectively, and that you have an appropriate amount of it. If, for example, your philosophy professor didn’t like it that you used a survey of public opinion as your primary evidence in your ethics paper, you need to find out more about what philosophers count as good evidence. If your instructor has told you that you need more analysis, suggested that you’re “just listing” points or giving a “laundry list,” or asked you how certain points are related to your argument, it may mean that you can do more to fully incorporate your evidence into your argument. Comments like “for example?,” “proof?,” “go deeper,” or “expand” in the margins of your graded paper suggest that you may need more evidence. Let’s take a look at each of these issues—understanding what counts as evidence, using evidence in your argument, and deciding whether you need more evidence.
Before you begin gathering information for possible use as evidence in your argument, you need to be sure that you understand the purpose of your assignment. If you are working on a project for a class, look carefully at the assignment prompt. It may give you clues about what sorts of evidence you will need. Does the instructor mention any particular books you should use in writing your paper or the names of any authors who have written about your topic? How long should your paper be (longer works may require more, or more varied, evidence)? What themes or topics come up in the text of the prompt? Our handout on understanding writing assignments can help you interpret your assignment. It’s also a good idea to think over what has been said about the assignment in class and to talk with your instructor if you need clarification or guidance.
Instructors in different academic fields expect different kinds of arguments and evidence—your chemistry paper might include graphs, charts, statistics, and other quantitative data as evidence, whereas your English paper might include passages from a novel, examples of recurring symbols, or discussions of characterization in the novel. Consider what kinds of sources and evidence you have seen in course readings and lectures. You may wish to see whether the Writing Center has a handout regarding the specific academic field you’re working in—for example, literature, sociology, or history.
A note on terminology: many researchers distinguish between primary and secondary sources of evidence (in this case, “primary” means “first” or “original,” not “most important”). Primary sources include original documents, photographs, interviews, and so forth. Secondary sources present information that has already been processed or interpreted by someone else. For example, if you are writing a paper about the movie “The Matrix,” the movie itself, an interview with the director, and production photos could serve as primary sources of evidence. A movie review from a magazine or a collection of essays about the film would be secondary sources. Depending on the context, the same item could be either a primary or a secondary source: if I am writing about people’s relationships with animals, a collection of stories about animals might be a secondary source; if I am writing about how editors gather diverse stories into collections, the same book might now function as a primary source.
Here are some examples of sources of information and tips about how to use them in gathering evidence. Ask your instructor if you aren’t sure whether a certain source would be appropriate for your paper.
Books, journals, websites, newspapers, magazines, and documentary films are some of the most common sources of evidence for academic writing. Our handout on evaluating print sources will help you choose your print sources wisely, and the library has a tutorial on evaluating both print sources and websites. A librarian can help you find sources that are appropriate for the type of assignment you are completing. Just visit the reference desk at Davis or the Undergraduate Library or chat with a librarian online (the library’s IM screen name is undergradref).
Sometimes you can directly observe the thing you are interested in, by watching, listening to, touching, tasting, or smelling it. For example, if you were asked to write about Mozart’s music, you could listen to it; if your topic was how businesses attract traffic, you might go and look at window displays at the mall.
An interview is a good way to collect information that you can’t find through any other type of research. An interview can provide an expert’s opinion, biographical or first-hand experiences, and suggestions for further research.
Surveys allow you to find out some of what a group of people thinks about a topic. Designing an effective survey and interpreting the data you get can be challenging, so it’s a good idea to check with your instructor before creating or administering a survey.
Experimental data serve as the primary form of scientific evidence. For scientific experiments, you should follow the specific guidelines of the discipline you are studying. For writing in other fields, more informal experiments might be acceptable as evidence. For example, if you want to prove that food choices in a cafeteria are affected by gender norms, you might ask classmates to undermine those norms on purpose and observe how others react. What would happen if a football player were eating dinner with his teammates and he brought a small salad and diet drink to the table, all the while murmuring about his waistline and wondering how many fat grams the salad dressing contained?
Using your own experiences can be a powerful way to appeal to your readers. You should, however, use personal experience only when it is appropriate to your topic, your writing goals, and your audience. Personal experience should not be your only form of evidence in most papers, and some disciplines frown on using personal experience at all. For example, a story about the microscope you received as a Christmas gift when you were nine years old is probably not applicable to your biology lab report.
Absolutely not. After you introduce evidence into your writing, you must say why and how this evidence supports your argument. In other words, you have to explain the significance of the evidence and its function in your paper. What turns a fact or piece of information into evidence is the connection it has with a larger claim or argument: evidence is always evidence for or against something, and you have to make that link clear.
As writers, we sometimes assume that our readers already know what we are talking about; we may be wary of elaborating too much because we think the point is obvious. But readers can’t read our minds: although they may be familiar with many of the ideas we are discussing, they don’t know what we are trying to do with those ideas unless we indicate it through explanations, organization, transitions, and so forth. Try to spell out the connections that you were making in your mind when you chose your evidence, decided where to place it in your paper, and drew conclusions based on it. Remember, you can always cut prose from your paper later if you decide that you are stating the obvious.
Here are some questions you can ask yourself about a particular bit of evidence:
Answering these questions may help you explain how your evidence is related to your overall argument.
There are many ways to present your evidence. Often, your evidence will be included as text in the body of your paper, as a quotation, paraphrase, or summary. Sometimes you might include graphs, charts, or tables; excerpts from an interview; or photographs or illustrations with accompanying captions.
When you quote, you are reproducing another writer’s words exactly as they appear on the page. Here are some tips to help you decide when to use quotations:
Be sure to introduce each quotation you use, and always cite your sources. See our handout on quotations for more details on when to quote and how to format quotations.
Like all pieces of evidence, a quotation can’t speak for itself. If you end a paragraph with a quotation, that may be a sign that you have neglected to discuss the importance of the quotation in terms of your argument. It’s important to avoid “plop quotations,” that is, quotations that are just dropped into your paper without any introduction, discussion, or follow-up.
When you paraphrase, you take a specific section of a text and put it into your own words. Putting it into your own words doesn’t mean just changing or rearranging a few of the author’s words: to paraphrase well and avoid plagiarism, try setting your source aside and restating the sentence or paragraph you have just read, as though you were describing it to another person. Paraphrasing is different than summary because a paraphrase focuses on a particular, fairly short bit of text (like a phrase, sentence, or paragraph). You’ll need to indicate when you are paraphrasing someone else’s text by citing your source correctly, just as you would with a quotation.
When might you want to paraphrase?
When you summarize, you are offering an overview of an entire text, or at least a lengthy section of a text. Summary is useful when you are providing background information, grounding your own argument, or mentioning a source as a counter-argument. A summary is less nuanced than paraphrased material. It can be the most effective way to incorporate a large number of sources when you don’t have a lot of space. When you are summarizing someone else’s argument or ideas, be sure this is clear to the reader and cite your source appropriately.
Sometimes the best evidence for your argument is a hard fact or visual representation of a fact. This type of evidence can be a solid backbone for your argument, but you still need to create context for your reader and draw the connections you want him or her to make. Remember that statistics, data, charts, graph, photographs, and illustrations are all open to interpretation. Guide the reader through the interpretation process. Again, always, cite the origin of your evidence if you didn’t produce the material you are using yourself.
Let’s say that you’ve identified some appropriate sources, found some evidence, explained to the reader how it fits into your overall argument, incorporated it into your draft effectively, and cited your sources. How do you tell whether you’ve got enough evidence and whether it’s working well in the service of a strong argument or analysis? Here are some techniques you can use to review your draft and assess your use of evidence.
A reverse outline is a great technique for helping you see how each paragraph contributes to proving your thesis. When you make a reverse outline, you record the main ideas in each paragraph in a shorter (outline-like) form so that you can see at a glance what is in your paper. The reverse outline is helpful in at least three ways. First, it lets you see where you have dealt with too many topics in one paragraph (in general, you should have one main idea per paragraph). Second, the reverse outline can help you see where you need more evidence to prove your point or more analysis of that evidence. Third, the reverse outline can help you write your topic sentences: once you have decided what you want each paragraph to be about, you can write topic sentences that explain the topics of the paragraphs and state the relationship of each topic to the overall thesis of the paper.
For tips on making a reverse outline, see our handout on organization.
You will need three highlighters or colored pencils for this exercise. Use one color to highlight general assertions. These will typically be the topic sentences in your paper. Next, use another color to highlight the specific evidence you provide for each assertion (including quotations, paraphrased or summarized material, statistics, examples, and your own ideas). Lastly, use another color to highlight analysis of your evidence. Which assertions are key to your overall argument? Which ones are especially contestable? How much evidence do you have for each assertion? How much analysis? In general, you should have at least as much analysis as you do evidence, or your paper runs the risk of being more summary than argument. The more controversial an assertion is, the more evidence you may need to provide in order to persuade your reader.
This technique may be easiest to use with a partner. Ask your friend to take on one of the roles above, then read your paper aloud to him/her. After each section, pause and let your friend interrogate you. If your friend is playing devil’s advocate, he or she will always take the opposing viewpoint and force you to keep defending yourself. If your friend is acting like a child, he or she will question every sentence, even seemingly self-explanatory ones. If your friend is a doubter, he or she won’t believe anything you say. Justifying your position verbally or explaining yourself will force you to strengthen the evidence in your paper. If you already have enough evidence but haven’t connected it clearly enough to your main argument, explaining to your friend how the evidence is relevant or what it proves may help you to do so.