Recency

Credible sources are also characterized by recency, or timeliness. Generally, because many aspects of life change constantly, newer evidence is more reliable than older evidence. For instance, when the Ebola virus epidemic first broke out in West Africa, September 2014 estimates indicated that there could be over a million cases by January 2015.9 Fortunately, a number of successful practices were instituted to limit the spread of the virus, and the actual number of cases by March 2015 was closer to 35,000.10 In general, if you have a choice between pieces of evidence from two equally credible sources and one is more current, you should select the more recent evidence.

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Of course, some evidence is classic and endures to this day. For example, although the teachings of Confucius are ancient, they command more respect today than the precepts of many contemporary philosophers. And the ideas of Machiavelli are still pertinent to the subject of international relations, even though they are almost five hundred years old. To decide whether evidence is outdated, ask yourself, “Has the claim made by my source become doubtful or false because of changing circumstances since the claim was made?”

To view someone citing sources and to assess the sources’ credibility, try Video Activity 7.2, “Citing Sources (Statistics and Testimony).”

With these criteria for source credibility in mind, let’s now look closely at three major strategies for researching your speech—using a library, searching the Internet, and interviewing experts in your topic.