Quantitative evidence includes things that can be represented in numbers: statistics, surveys, polls, census information. This type of evidence can be persuasive in its appeal to logos. Amy Domini cites numerical evidence in her essay to support her contention that “[f]ast food is a way of life. In America, the average person eats it more than 150 times a year. In 2007, sales for the 400 largest U.S.-based fast-food chains totaled $277 billion, up 7 percent from 2006” (see p. 87).
Quantitative evidence need not be all percentages and dollar figures, however. In an article on American education, Fareed Zakaria compares the education situation of the United States with that of other countries by citing quantitative information without a lot of numbers and figures.
U.S. schoolchildren spend less time in school than their peers abroad. They have shorter school days and a shorter school year. Children in South Korea will spend almost two years more in school than Americans by the end of high school. Is it really so strange that they score higher on tests?
If South Korea teaches the importance of hard work, Finland teaches another lesson. Finnish students score near the very top on international tests, yet they do not follow the Asian model of study, study and more study. Instead they start school a year later than in most countries, emphasize creative work and shun tests for most of the year. But Finland has great teachers, who are paid well and treated with the same professional respect that is accorded to doctors and lawyers. They are found and developed through an extremely competitive and rigorous process. All teachers are required to have master’s degrees, and only 1 in 10 applicants is accepted to the country’s teacher-training programs.
Zakaria includes quantitative data—two more years of school for Korean students than their American counterparts, a highly competitive process for teacher-training programs that accept only one of every ten applicants—as part of his overall discussion. He could have cited dollar amounts as evidence of how well paid teachers are in Finland, but in the context of this column he makes the point and moves on; perhaps if he were writing for a more scholarly or skeptical audience, he would have thought it necessary to provide even more information.
Bandwagon appeal (or ad populum fallacy) occurs when evidence boils down to “everybody’s doing it, so it must be a good thing to do.” Sometimes, statistics can be used to prove that “everybody’s doing it” and thus give a bandwagon appeal the appearance of cold, hard fact.
| example | You should vote to elect Rachel Johnson—she has a strong lead in the polls! |
Polling higher does not necessarily make Senator Johnson the “best” candidate, only the most popular.