Statistics are collections of numerical facts:

These statistics were gathered from a reliable source, the National Institute of Alcohol Abuse and Alcoholism Web site. Such data can be used in an argument for alcohol education and treatment intervention programs targeted at teens or young adults.

Writers and politicians often use statistics in selective ways to bolster their views. If you suspect that a writer’s handling of statistics is not quite fair, look at the data yourself and see whether they check out. Read authors with opposing views, who may give you a fuller understanding of the numbers.

Arguments supported by statistics

In the following passage, the writer uses statistics to show that college students carry unreasonably high credit debt.

A 2009 study revealed that undergraduates are carrying record-high credit card balances and are relying on credit cards more than ever, especially in the economic downturn. The average credit card debt per college undergraduate is more than three thousand dollars, and three-quarters of undergraduates carry balances and incur finance charges each month (Hunter).

In her review of research on attention deficit hyperactivity disorder (ADHD), psychology student Valerie Charat chooses careful wording when she evaluates the data on whether ADHD is more prevalent in boys than in girls.

Some studies have claimed a 3:1 ratio of boys with ADHD to girls with ADHD (American Psychiatric Association, 1987), while others have cited ratios as high as 9:1 (Brown et al., 1991). The differences in prevalence have been attributed to a variety of causes, one of which is that girls may have more internalized symptoms and may be overlooked in ADHD diagnoses (Brown et al., 1991).