[Auracle]

Even their abstract seems biased:

"...and price increases of about 1.5 percent— or about 6 cents on a four-dollar hamburger."

Ah, yes, the fabled four-dollar hamburger. I know I never need to spend more than 4 dollars nowadays when I get fast food.

[Spivak]

A hamburger is at McDonalds is $1.89 in my area, a McDouble is $3.29. The double cheeseburger is $3.99. What they call the "daily double" which is a silly name for a hamburger with the works is also $3.99.

I don't think using the basic burgers is a bad choice since specialty burgers probably don't compare well across chains.