Statistics can be a powerful persuasive tool in public speaking if the speaker appropriately explains their use and significance.

Understanding Statistics

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.

Guidelines for Helping Your Audience Understand Statistics

• Use reputable sources for the statistics you present in your speech such as government websites, academic institutions and reputable research organizations and policy/research think tanks.
• Use a large enough sample size in your statistics to make sure that the statistics you are using are accurate (for example, if a survey only asked four people, then it is likely not representative of the population’s viewpoint).
• Use statistics that are easily understood. Many people understand what an average is but not many people will know more complex ideas such as variation and standard deviation.
• When presenting graphs, make sure that the key points are highlighted and the graphs are not misleading as far as the values presented.
• Statistics is a topic that many people prefer to avoid, so when presenting statistical idea or even using numbers in your speech be sure to thoroughly explain what the numbers mean and use visual aids to help you explain.

Common Uses of Statistics in a Speech

Some common uses of statistics in a speech format may include:

• Results from a survey and discussion of key findings such as the mean, median, and mode of that survey.
• Comparisons of data and benchmarking results—also using averages and comparative statistics.
• Presenting findings from research, including determining which variables are statistically significant and meaningful to the results of the research. This will likely use more complicated statistics.

Common Misunderstandings of Statistics

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.

Communicating Statistics

Graphs, tables, and maps can be used to communicate the numbers, but then the numbers need to be put into context to make the message stick.

Introduction

Credibility makes our messages believable, and a believable message is more likely to be remembered than one that is not. But gaining credibility is not so easy. As Chip and Dan Heath note in Made to Stick:

If we’re trying to persuade a skeptical audience to believe a new message, the reality is that we’re fighting an uphill battle against a lifetime of personal learning and social relationships.

So how can we add credibility to our words? One way is to rely on statistics.

Putting Statistics into Context for Our Audiences

We are so used to resorting to statistics that we tend to bombard our audiences with too many mind-numbing numbers. As the Heaths state:

Statistics are rarely meaningful in and of themselves. Statistics will, and should, almost always be used to illustrate a relationship. It’s more important for people to remember the relationship than the number.

We need to put statistics into context for our audiences. In the book, the Heaths give several good examples of others who have done this. For example, they introduce us to Geoff Ainscow, one of the leaders of the Beyond War movement in the 1980s.

Ainscow gave talks trying to raise awareness of the dangers of nuclear weapons. He wanted to show that the US and the USSR possessed weapons capable of destroying the earth several times over. But simply quoting figures of nuclear weapons stockpiles was not a way to make the message stick. So, after setting the scene, Ainscow would take a BB pellet and drop it into a steel bucket where it would make a loud noise. The pellet represented the bomb that was dropped on Hiroshima. Ainscow would then describe the devastation at Hiroshima. Next, he would take 10 pellets and drop them in the bucket where they made 10 times as much noise. They represented the nuclear firepower on a single nuclear submarine. Finally, he poured 5,000 pellets into the bucket, one for each nuclear warhead in the world. When the noise finally subsided, his audience sat in dead silence.

That is how you put statistics into context.

Using Tables, Graphs and Maps to Communicate Statistical Findings

The story of communicating your statistics does not end with putting them into context. Actually, it would be better to say that it does not begin with putting the numbers into context. In reality, the story you are telling through your evidence will probably start with the display of a table, graph, or map.

A simple table, graph, or map can explain a great deal, and so this type of direct evidence should be used where appropriate. However, if a particular part of your analysis represented by a table, graph, or map does not add to or support your argument, it should be left out.

While representing statistical information in tables, graphs, or maps can be highly effective, it is important to ensure that the information is not presented in a manner that can mislead the reader. The key to presenting effective tables, graphs, or maps is to ensure they are easy to understand and clearly linked to the message. Ensure that you provide all the necessary information required to understand what the data is showing. The table, graph, or map should be able to stand alone.

Tables, graphs, and maps should:

• relate directly to the argument;
• support statements made in the text;
• summarize relevant sections of the data analysis; and
• be clearly labelled.

Table Checklist

• Use a descriptive title for each table.
• Label every column.
• Provide a source if appropriate.
• Minimize memory load by removing unnecessary data and minimizing decimal places.
• Use clustering and patterns to highlight important relationships.
• Use white space to effect.
• Order data meaningfully (e.g., rank highest to lowest).
• Use a consistent format for each table.

Also, do not present too much data in tables. Large expanses of figures can be daunting for an audience, and can obscure your message.

Graph Checklist

• Title: Use a clear, descriptive title.
• Type of graph: Choose the appropriate graph for your message, avoid using 3D graphs as they can obscure information.
• Axes: Decide which variable goes on which axis, and what scale is most appropriate.
• Legend: If there is more than one data series displayed, always include a legend, preferably within the area of the graph.
• Labels: All relevant labels should be included.
• Color/shading: Colors can help differentiate; however, know what is appropriate for the medium you’re using.
• Data source: Provide the source of data you’ve used for the graph.
• Three-Quarters Rules: For readability, it’s generally a good rule of thumb to make the y-axis three-quarters the size of the x-axis

Expert versus Peer Testimony

There are three types of testimonials that fall into the range of expert to peer testimony; knowing your audience leads to the best choice.

Testimony

A testimony is a statement or endorsement given by someone who has a logical connection to the topic and who is a credible source.

Testimony can be used to either clarify or prove a point and is often used by referring to the research of experts. For example, you could quote a study conducted by an independent auditing organization that endorses your organization’s ability to financially support current workforce levels.

There are three major types of testimonies, ranging from expert to peer testimony. They are:

• Expert authorities
• Celebrities and other inspirational figures
• Peer

Expert Authorities

First, we can cite expert authorities. According to Chip and Dan Heath in their book Made to Stick, an expert is “the kind of person whose wall is covered with framed credentials: Oliver Sacks for neuroscience, Alan Greenspan for economics [well, maybe not such a great example any longer], or Stephen Hawking for physics.”

If an expert supports our position, it usually adds credibility. If we are giving a presentation on a medical issue and can find support for our position in prestigious medical reviews such as The New England Journal of Medicine or The Lancet, it would probably be a good idea to cite those authorities.

Celebrities and Other Inspirational Figures

Second, we can refer to celebrities and other inspirational figures. Take the example of Oprah Winfrey recommending a book. Her recommendations influence the book-buying habits of thousands of people. Why? Because “if Oprah likes a book, it makes us more interested in that book. We trust the recommendations of people whom we want to be like,” note the Heaths.

But what if there are no “experts” or “celebrities” to be found? Well, hold on a minute. They might be closer than you think. Do you have positive feedback from satisfied customers? Is there someone on your team (including you) with certain educational background or work experience that is relevant? If so, they (or you) might be able to provide the expertise that you seek, even if they are not widely known.

Peer 

Peer testimony comes from a source that is neither expert nor celebrity, but similar status to the audience.

They cite the example of Pam Laffin, a mother of two who died at the age of 31 from emphysema-related lung failure caused by years of smoking. She appeared in several anti-tobacco commercials sponsored by the Massachusetts Department of Public Health. The commercials were difficult to watch but highly effective; Pam Laffin told a compelling story in a way that more famous people could not.

What to Consider Before Using Testimony

Before using testimony, ask:

• Is the material quoted accurately?
• Is the source biased, or perceived as biased?
• Is the source competent in the field being consulted?
• Is the information current?

In the end, your choice as to which type of testimony you use will depend on your audience.

Smokers, for example, know all of the hazards of smoking and still continue to smoke. Give them a presentation on the dangers of smoking using expert testimony and you’ll probably be met with a response like, “Yeah, but it won’t happen to me.” Use a peer like Pam Laffin, however, and the response will be totally different.

Here is a young woman who probably also thought that it wouldn’t happen to her, speaking “from her grave.” Smokers can relate to her. She isn’t just a numerical figure. This type of testimony is quite effective when you’re trying to tell people the dangers of doing something.

So, get to know your audience, put yourself in their place, and choose the type or combination of evidence that will make your message stick.

How to Incorporate Expert Testimony

When a claim or point is made during a speech, the audience initially may be reluctant to concede or agree to the validity of the point. Often this is because the audience does not initially accept the speaker as a trustworthy authority. By incorporating expert testimony, the speaker is able to bolster their own authority to speak on the topic.

Therefore, expert testimony is commonly introduced after a claim is made. For example, if a speech makes the claim, “Manufacturing jobs have been in decline since the 1970s,” it should be followed up with expert testimony to support that claim. This testimony could take a variety of forms, such as government employment statistics or a historian who has written on a particular sector of the manufacturing industry. No matter the particular form of expert testimony, it is incorporated following a claim to defend and support that claim, thus bolstering the authority of the speaker.

Once you have found experts to support your ideas, you may wonder how to incorporate their testimony into your speech. The following will give you an idea of how to incorporate expert testimony in order to support your argument and improve your speech.

Example of Incorporating Expert Testimony

Search for and watch a TED talk by Barry Schwartz, a Professor of Social Theory and Social Action at Swarthmore College and author of numerous books in the field of psychology and economics. Notice how Schwartz references expert testimony in the course of his speech to justify his point to the audience.

Schwartz begins by showing the job description of a hospital janitor, noting that the tasks do not require interaction with other people. However, Schwartz introduces the expert testimony of actual hospital janitors as a way to complicate the apparent solo nature of janitorial work. Schwartz personalizes the experts with proper names, “Mike,” “Sharleene,” and “Luke,” and uses their testimony to demonstrate that despite the job description, janitors take social interaction to be an important part of their job.

In this instance, Schwartz incorporates the expert testimony of actual janitors as a both a foil and a support. The testimony shows that in fact janitorial work does include interaction with other people, thus foiling the initial presentation of janitorial work as solitary. In addition, Schwartz uses the testimony of these experts to show that they embody the characteristics of wisdom that Schwartz will describe in the remainder of the speech.