Okay... I think I am settling on the idea of research the popularity of Newberry award-winning books. There was recently an article by Anita Silvey, critiquing the most recent Newberry winners (Has the Newbery Lost Its Way?).
This opens the door for some real-world research. Silvey references some favorite Newberry's in the past, such as Charlotte's Web. These were/are books that kids love! Silvey argues that the recent books are not as popular with children... that "It’s possible in an age of sequels that committee members have unintentionally gravitated toward quirky offerings. But valuing uniqueness over universality has often led judges down the wrong road."
So, my new plan is to look at circulation records in school libraries of the Newberry Winners from the last 10 (?) years. To keep things uniform, I will look at the circulation records of each Newberry winner in the year after winning the award (clearly, it would be unfair for me to say that Charlotte's Web has been checked out a million times and is therefore the better book.... if Good Masters, Sweet Ladies has had half that amount of time to gain momentum.) Also, because Newberry is primarily for children's literature, I am going to look in a couple elementary/middle schools.
So, those are my ideas so far!