Types of Supporting Evidence
Facts
Facts are something that is known or can be proven to be true. Because facts can be proven, they provide powerful evidence for a speaker. Facts are useful to establish credibility.
Expert Opinion
Supporting evidence gathered from known experts carries a great deal of credibility. Remember that the people cited should be perceived as experts by others in the same field of expertise. Thus the author of a self-help book on psychology that has been rejected by professional psychologists would not be a considered an expert source. Also make sure the expert is talking about a topic in their area of expertise; an expert physicist is not necessarily an expert on psychological matters. Your testimony should also come from unbiased, third party sources. For example, the maker of a particular drug may not be an unbiased source on the attributes of that drug.
Examples
Examples are useful to illustrate your topic or to clarify complex issues.
Stories or Anecdotes
Personal experiences, your or others, lend a real life touch to a topic. When using personal experience consider whether or not the experience is consistent with other supporting evidence such as fact and expert opinion. Make sure the story you choose is appropriate to the point you would like to make.
Types of Information Sources
Primary vs. Secondary Sources
- Primary sources are firsthand or eyewitness accounts. They present the actual evidence of an event without any analysis or interpretation. Primary sources include diaries, letters, legal or court documents, laws, speeches, statistics, journals, original research documents, and the like.
- Secondary sources analyze, interpret, retell, explain, or critique primary sources.
Scholarly vs. Popular Sources
- Scholarly sources are written by the experts in the subject matter. They are often written for use by other scholars, researchers, or serious students of the subject. They often use language that is specific to that discipline. They usually include in-text citations or footnotes and a works cited or bibliography. They are often peer-reviewed, meaning the article has been anonymously reviewed by a panel of experts in the topic before it has been accepted for publication. They are usually published by a professional organization, research center, or scholarly press.
- Popular sources are written for a more general audience, not necessarily expert in the topic. They are often written by journalists or others who are not professionals in the field. They are written in easy to understand language; they do not use technical jargon. Although they may have footnotes and/or citations, they are usually not as extensive. There may be little or no editorial review.
Popular sources should not necessarily be seen as less worthy than scholarly. They are often very reputable sources of information that has been distilled so that it can be easily understood by the non-professional. Each source must be judged individually.
Print Sources vs. Online Sources vs. Web Sources
Criteria for Evaluating Sources
Authority
- Who is the author of the source (a person, an organization, or a company)?
- Is the author an expert on the topic? To what extent does the author's occupation, years of experience, position, or education make him/her an expert?
- What do you know about the publisher (e.g. company, professional association) of the source?
Purpose
- Does the source try to sell, inform, or try to persuade you of a certain point of view?
- Is it a commercial, governmental, or educational institution source?
Currency
- Is the source up to date in relation to the topic?
Accuracy
- Is the information based on facts or opinions?
- Does the author provide any supportive evidence for his/her statements?
- Are there sources listed for any information presented as fact so that they can be looked for to verify the facts?
Citing Sources
What does "citing sources" mean
Citing or crediting sources means verbally acknowledging the source from which you have drawn your information and ideas. In the body of a research paper, you give credit to authors you have quoted or paraphrased. Similarly, when you use other people’s words or ideas in your speech, you must credit the source orally when delivering the speech. (If not, it is considered a form of plagiarism.)
Remember:
You must cite your source if you are
- directly quoting (word for word)
- paraphrasing someone else's idea in your own words
- borrowing someone else's ideas on how to organize your speech
- using illustrations, diagrams, etc. that you have not produced yourself
You need not cite when
- presenting your own original ideas
- discussing ideas that are commonly known (the sun comes up in the east)
Why cite sources
It is important for your audience to know where your information came from, if the sources were impartial, as well as how current the sources were. Things change rapidly in today’s society and something that was true a few years ago is not necessarily true today. Anybody can publish just about anything on a web site. In persuasive speaking, it is also essential that your audience accepts the credibility of your evidence; this is achieved by citing of sources. Thus, the citing of sources also adds to your credibility as a speaker.
How to do an oral citation
As a rule of thumb, these are three basic elements, but this will vary with the type of source:
- WHO: Who is the author and are any credentials known? Who is interviewed? Who wrote the book/article? Who is behind the website or who sponsors the website?
- WHAT: What is the title of the source—book, journal, magazine, newspaper or webpage? What type of publication is it—newspaper, government report, magazine, journal? (In other words, would everybody know that the Kansas City Star is a newspaper? If not, tell them!)
- WHEN: When was the book, magazine, newspaper or journal published (date)? When was the person interviewed? When was the website last updated and/or when did you access the website?
More specifically----
Articles
- If you are quoting an article in a periodical/publication--magazine, newspaper, journal-- give a quick statement of the author (if relevant) as well as the (full) date and title of the periodical: (=publication = name of the newspaper, magazine or journal) This includes print sources as well as those found in the Library Databases.
- “According to Len Zehm, a sports columnist for the Chicago Sun Times, in an article from May 31, 2006…”
- “Newsweek magazine of December 4, 2005 lists bankruptcy as the…”
- “In the latest Gallup Poll, cited in last week’s issue of Time magazine…”
- You do not need to give the title of the article, although you may if it helps in any way. For example, if you are quoting one or more articles from the same newspaper, this would help differentiate the sources.
- If the periodical is not readily recognized, offer a comment of explanation:
- "In the March 2005 issue of Patient Care, a magazine devoted to nursing, hospitals…”
- “The Winter 2006 issue of Communication Education, a journal published by the National Communication Association, Professor Ruth Anne Clark’s article…”
- You do not need to give the page number nor the name of electronic database that cataloged the periodical/publication.
Books
- If you are citing information from a book, give the title of the book, a quick statement of the author (& brief credentials), and the year of publication. You don’t have to mention the page, publisher or city of publication:
- "In his book, Eating to Be Smart, published in 2005, Charles Larson, a registered dietician, notes that consuming yogurt…”
Web pages
- If you are citing a Web Page (site) you need to establish the credibility, currency and objectivity (fact vs. opinion) of the site. Mention
- the title of the Web Page
- the “author”/organization/sponsor that supports the site
- the site’s “credentials” You can confirm a site’s “credentials” by looking for links as: “About us” or “Our Mission” or “Who we are”
- the last date it was updated, if known (In Netscape, you can click on “view” and then “page info” for date of last update.)
- the date you accessed the site.
- Question: If you cannot confirm any of this info, would it be prudent to still quote from the Web Page?
- “One of the most active developers of neurotechnology, Cyberkinetics.com, claims on their website last updated on March 24, 2006 that…”
- “From the Web Page maintained by the Wisconsin Council of Dairy Farmers entitled “Dairy Products and Your Diet”, as of January 10, 2007, yogurt…” (or “of an unknown date which I accessed on September 18th of this year”), yogurt proves to be…”
- In an oral citation of a Web Page, you do not need to give the URL.
- Caution: If a Web Page quotes a book, magazine or newspaper, unless YOU READ the book/magazine/newspaper quoted, your source IS the Web Page, NOT the book/magazine/newspaper. You obtained the quote from the Web Page, not the original text or article. Remember Web Pages can quote out of context.
- “From a Web Page supported by Beconvinced.com, a commercial website promoting the religion of Islam, the book Principles of Oceanography is quoted as stating that…”
Interviews
- If you are quoting the source of an interview, give the person's name and statement of their credentials, date of interview, as well as the fact that the information was obtained from a personal interview:
- “In a personal interview on January 15 that I had with Nancy Manes, head of cardiac care at Central DuPage Hospital, the most important…”
- Caution: Interviews are not the same as conversations or undocumented recollections of professors’ comments in class lectures and must come from credentialed “experts” in the field quoted.
Why practice oral citations
Without practice, oral citation of sources is often a difficult concept for students to incorporate into their speeches because verbally presenting source references interrupts the flow of thoughts and ideas researched. Speakers often are concentrating more on content, rather than worrying about where they sourced the information. Accordingly, incorporate oral source citations into each of your speech rehearsals. Citations become part of the overall timing of the speech, so use a watch or timer when practicing.
Tip: Do not say quote, unquote when you cite a direct quotation. Pause briefly instead.
How to do written citations (works cited)
Follow the citation format requested by your instructor. The Library has a list of resources to assist you with your written citations.
Updated 21 June 2007
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