This CNN article on the American prison system relies on numbers and statistics to prove a point: No other country comes close to America's rate of incarceration.
This article does a good job summarizing the statistics it uses to convey a clear message to the reader. The numbers they use are not confusing and are rather straightforward. For example, the article says "(Americans) make up 5 percent of the world's population, but (American prisoners) make up 25 percent of jailed prisoners (in the world)." Furthermore, it says "No other country comes even close to our rates of incarceration. We have 760 prisoners per 100,000 people."
It also includes this piece of information: "In the past two decades, the money that states spend on prisons has risen at six times the rate of spending on higher education. In 2011, California spent $9.6 billion on prisons, versus $5.7 billion on higher education. Since 1980, California has built one college campus; it's built 21 prisons. The state spends $8,667 per student per year. It spends about $50,000 per inmate per year."
The information is clearly presented (though it is not clearly cited) so that a person as young as 11 or 12 could understand the basic concept the article is about.
The article is well written, as it is not extremely long yet expresses a clear message. Including the data that they did is crucial for the success of the article; without these stats and facts to back it up, the article is useless as it would provide the reader with no scope on the issue.
To me, it seems that the reporter did not do all the math himself. It looks as if he obtained this information from some sort of public record database or from what other people said. The author of the article cited an article in the New Yorker by Adam Gopnik and quoted Pat Robertson multiple times. I feel that more direct citations would have strengthened his argument.