Tests of Evidence

In order to tell us how you know something, you need to tell us where the information came from.  If you personally observed the case you are telling us about, you need to tell us that you observed it, and when and where.  If you read about it, you need to tell us where you read about it.  If you are accepting the testimony of an expert, you need to tell us who the expert is and why she is an expert in this field.  The specific identity (name, position) and qualifications of your sources are part of the answer to the question "How do you know?"  You need to give your readers that information. 

Keep in mind that it is the person, the individual human being, who wrote an article or expressed an idea who brings authority to the claim.  Sometimes that authority may be reinforced by the publication in which the claim appeared.  Sometimes not.  But when you quote or paraphrase a source you are quoting or paraphrasing the author, not the magazine or journal.

So if you were introducing a source on the effects of progressive education, which of the following would sound more persuasive:

• "An article in an education journal says that the progressive movement failed because most teachers never adopted it." 
• "An article in The Harvard Education Review reports that the progressive movement failed because most teachers never adopted it."
• "Richard Elmore, a professor at Harvard's Graduate School of Education, concludes that the progressive movement failed because most teachers never adopted it."

The last example is the most persuasive because it is the most specific.  The name and qualifications of the source are the most important information in establishing the credibility of your evidence.  Never omit them.  Usually the best way to introduce a quotation is to make the name of the person you are quoting the subject of your sentence.

Of course, sometimes the source will not be an individual author but several people or an agency or group.  Always report the authorship as it is presented on the title page of the work.

Whether you find your information from a published or broadcast source, whether you are quoting it directly or not, you need to list the source in your list of works cited and cite it correctly in the text. 

EIGHT WAYS TO TEST SOURCES OF EVIDENCE

1. Relevance: Is the evidence presented really relevant to the claim being made and the subject at hand?
2. Recency: Has the situation described by the evidence changed since its publication? If so, the evidence is likely irrelevant to a current discussion. (However, just being old isn't enough to disqualify evidence: The situation must have changed since the evidence was published.)
3. Validity: Is the source what it appears to be or is it a fraud or forgery?
4. Identification: Is the source clearly identified? Scholars do not rely on "anonymous." Specific authorship is preferred.
5. Expertise: Is the source qualified to provide this evidence? Sources may be qualified by training/education or by experience with the topic of the evidence.
6. Bias: Does the source have an interest in the topic of the evidence that might distort the evidence? (Note: Reluctant testimony, in which the source testifies against self-interest (e.g., a Republican blaming the Republican Party) is very persuasive.) Biased sources do not always distort their evidence, but their comments on the evidence often reveal pathos.
7. Internal Consistency: Is the information consistent within itself or does the evidence contradict itself?
8. External Consistency: Is the evidence consistent with outside qualified sources?

These comments retrieved from: John Tagg, Palomar College - http://daphne.palomar.edu/handbook/support.htm AND  http://www.itc.csmd.edu/lan/vclements/Evidence.htm