Take book bestseller lists as an example. A book that makes it to the top of the New York Times bestseller list can proudly display "#1 New York Times Bestseller" on its book jacket. The publishers hope that you will be in a bookstore, see the book, and think, "If everyone else is reading it and buying it, then why aren't I?"

There are many book bestseller lists, but the most widely discussed and quoted lists appear in the weekly New York Times Book Review. When those lists change, it's news. In late July of 2000, the New York Times restructured its bestseller lists for the first time in 16 years. Among the changes was the addition of children's book lists. And the reason for the changes was... Harry Potter.

Up until the change in the New York Times bestseller lists, its main bestseller list for fiction had been dominated by the books in the Harry Potter series by J. K. Rowling. Not coincidentally, the New York Times made the change just as the fourth book in the series was being released. Creating the children's bestseller lists meant that the New York Times could move the Harry Potter books off the "main" hardcover fiction list and onto the new children's list.

In an interview with the Boston Globe, New York Times Book Review editor Charles McGrath gave this reason for the changes, "The sales and popularity of children's books can rival and, in the case of the Harry Potter books, even exceed those of adult books. With a separate children's list, we can more fully represent what people are reading, and we can clear more room on the adult list for adult books." Supporters of the move — particularly publishers other than Harry Potter publisher, Scholastic Press — were happy to see the hardcover fiction list opened up for different books (i.e. their books).

Not everyone was convinced. Critics claimed that the New York Times was out of touch with the public, that a large percentage of the series' readers were adults, and that any books that sold as well as the Harry Potter books deserved to be on the main bestseller list. But the list changes remained and, rather than Harry Potter appearing in four of the top ten spots in the main hardcover fiction list, Harry Potter "disappeared" onto the children's lists.

• Students can read a discussion of last year's reorganization of the New York Times Book Review bestseller list in the CNN.com article, "Why 'Harry Potter' did a Harry Houdini."

• Interpreting Pie Charts: Students compare the sales of three games in relation to one another and display the data on a pie chart.
• Defining the Mean and Median: Students are introduced to interpretation of raw data, including the concepts of sample, central tendency, mean, and median.
• Defining the Mode: Students learn about mode in a data set.
• Calculating the Mean, Median, & Mode: Students apply the concepts of mean , median, and mode to a data set.

Analyzing the Problem

1. Have students read the article, "Why 'Harry Potter' did a Harry Houdini" and compare the data source of the New York Times bestseller list with that of Amazon.com's "Hot 100" list. Here are questions they may want to consider:
   
   
   • Are these two bestseller lists drawing on similar samples? How are the samples similar? How are they different?
   • How might the differences in the sample sets affect the raw data?

2. Have students look at the Publishers Weekly article, "Bestsellers of 1999—Hardcover: So Far, Little Has Changed." At the bottom of the article, they will find a fiction and a nonfiction list of the top 15 hardcover sellers in 1999. Draw a bar chart for each of the lists.
   

3. Have students examine this week's USA Today's Top 150 best-selling books list and answer these questions:
   
   
   • Can you draw a bar chart representing the top 10 sellers? Why or why not?
   • If the #1 book has been on the list for 2 weeks, and the #2 book has been on the list for 4 weeks, can you determine which book has sold more copies? Why or why not?
   • Does the number of book sales correspond to numbers of readers? Why not? (Hint: Do you buy every book you read?)

1. Temple University professor of mathematics John Allen Paulos writes a monthly column, "Who's Counting?" for ABCNEWS.com. He addressed the issue of top 10 lists in the article, "The Rankings Game: Mirror, Mirror, Who's the Most Beautiful of All?"
   

2. Students can look at current lists and ratings, and learn more about how ratings are created, at the following sites:
   
   
   • Most recent weekly Nielsen ratings for television, as well as the Nielsen Media Research site
   • Box Office Report, with reports on the most recent weekly top 10 grossing films and the top grossing films of 2001
   • The Billboard 200™ top 100 albums (CDs or cassettes, etc.) by sales for the most recent week