## Using & **Understanding Statistics**

**Statistics **are a systematic collection, analysis, comparison, and interpretation of numerical data of data. As evidence, they are useful in summarizing complex information, quantifying, or making comparisons. Statistics are powerful pieces of evidence because numbers appear straightforward. Numbers provide evidence that quantifies, and statistics can be helpful to clarify a concept or highlighting the depth of a problem.

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

We often know a statistic when we find one, but it can be tricky to understand how a statistic was derived.

You may have heard the terms **mean, median, **and **mode **during math class. The **mean **is the arithmetic average for a data set, which is equal to the sum of the numerical values divided by the number of values. You can determine the mean (or average) by adding up the figures and dividing by the number of figures present. If you’re giving a speech on climate change, you might note that, in 2015, the average summer temperature was 97 degrees while, in 1985, it was just 92 degrees. The **mode **is the value that appears the most often in a data set. The **median **is described as the numerical value separating the higher half of a sample, a population, or a probability distribution, from the lower half. For example, your professors may use these values when discussing exam results with the entire class, to determine how “well” the class performed overall.Averages and percentages are two common deployments of statistical evidence.

When using statistics, comparisons can help translate the statistic for an audience. In the example above, 97 degrees may seem hot, but the audience has nothing to compare that statistic to. The 30-year comparison assists in demonstrating a change in temperature.

A **percentage** expresses a proportion of out 100. For example, you might argue that “textbook costs have risen more than 1000% since 1977” (Popken, 2015). By using a statistical percentage, 1000% sounds pretty substantial. It may be important, however, to accompany your percentage with a comparison to assist the audience in understanding that “This is 3 times higher than the normal rate of inflation” (UTA Libraries). You might also clarify that “college textbooks have risen more than any other college-related cost” (Bureau of Labor Statistics, 2016).

You are responsible for the statistical information that you deploy. It’s all too common for us as information consumers to grab a quick statistic that sounds appealing, but that information may not be reliable.