10.5: Statistics
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Using statistics in public speaking can be a powerful tool. It provides a quantitative, objective, and persuasive platform on which to base an argument, prove a claim, or support an idea. Before a set of statistics can be used, however, it must be made understandable by people who are not familiar with statistics. The key to the persuasive use of statistics is extracting meaning and patterns from raw data in a way that is logical and demonstrable to an audience. There are many ways to interpret statistics and data sets, not all of them valid.
A common misunderstanding when using statistics is “correlation does not mean causation.” This means that just because two variables are related, they do not necessarily mean that one variable causes the other variable to occur. For example, consider a data set that indicates that there is a relationship between ice cream purchases over seasons versus drowning deaths over seasons. The incorrect conclusion would be to say that the increase in ice cream consumption leads to more drowning deaths, or vice versa. Therefore, when using statistics in public speaking, a speaker should always be sure that they are presenting accurate information when discussing two variables that may be related. Statistics can be used persuasively in all manners of arguments and public speaking scenarios—the key is understanding and interpreting the given data and molding that interpretation towards a convincing statement.
Evaluating Information
The popular online encyclopedia, Wikipedia, is a great resource for general information. It is a good place to start in order to determine search terms and potentially relevant strains of thought on a given topic. However, it is not the most credible source to cite in your speech. Since anyone can update the site at any time, information may be entirely inaccurate. When using Wikipedia, look for source citations and follow the links to original source material.
To determine whether or not the information is comprehensive, check to see that it thoroughly covers the issue, considers competing perspectives, and cites the sources where supporting material came from. First, check to see that your source not only discusses issues that pertain to your topic, but thoroughly explains the reasoning behind the claims it offers. Often you will already be familiar with the topic, but you will require the addition of strong reasoning to properly support your ideas. If your source cannot provide strong reasoning, it is not the best quality source.
Second, determine whether the source considers competing perspectives. If your source does not also recognize and consider opposing arguments, it is not the best quality source. Third, check to see that your source offers supporting data and or if it includes non-credible citations, it is not the best quality source. It is fine to use a source that is weak in one of these areas if you still find it compelling, but know that you may need to back it up with additional credible information. If the source is weak in multiple areas, do your best to avoid using it so that it does not weaken your speech.
In addition to the quality, you should examine source credibility. When evaluating credibility, focus on the sources’ qualifications, the parity of their message with similar sources, and their biases. One of the most important elements of credibility is qualification. Sometimes qualifications will be linked to a person’s profession. For example, if you are talking about earthquakes, you might want the expertise of a seismologist who studies earthquake waves and their effects. However, professional expertise is not the only type of credibility. If you want to discuss the feeling of experiencing a major earthquake, testimony from a survivor may be more credible than testimony from a scientist who studied the event but did not experience it. When examining credibility, check to see that the person has the training or experience appropriate to the type of information they offer. Next, check to see whether the information in your chosen source aligns with information in other sources on the issue. If your source is the only one that offers a particular perspective, and no other source corroborates that perspective, it is less likely to be credible.
Additionally, check for bias. All sources have bias, meaning they all come from a particular perspective. You must check to see whether the perspective of the source matches your own, and whether the perspective overwhelms the ability to offer reliable information on an issue. Also check to see whether the source is affiliated with organizations that are known to hold a particularly strong opinion concerning the issue they are speaking to.
In your speech, make reference to the quality and credibility of your sources. Identifying the qualifications for a source, or explaining that their ideas have been used by many other credible sources, will enhance the strength of your speech. You may be tempted to stop once you have found one source that supports your idea, but continuing to research and comparing the information in each source will help you better support your ideas. It will also prevent you from overlooking contradictory evidence that you need to be able to address.