New York Times bestseller list

Something that I have been meaning to keep tabs on for a while now is the New York Times bestseller list. Took me a while to get around to actually looking up the URL for it (which is http://www.nytimes.com/pages/books/bestseller/ if you're wondering), but I have finally got around to it.

I'm only really interested in two lists. The two adult fiction list. The top five out of each of those for today are.... (drumroll anyone?)

HARDCOVER FICTION
1. A THOUSAND SPLENDID SUNS, by Khaled Hosseini
2. THE OVERLOOK, by Michael Connelly
3. THE 6TH TARGET, by James Patterson and Maxine Paetro
4. INVISIBLE PREY, by John Sandford
5. BAD LUCK AND TROUBLE, by Lee Child

PAPERBACK FICTION
1. THE HUSBAND, by Dean Koontz
2. WATER FOR ELEPHANTS, by Sara Gruen
3. THE KITE RUNNER, by Khaled Hosseini
4. THE MEMORY KEEPER’S DAUGHTER, by Kim Edwards
5. THE ROAD, by Cormac McCarthy

I want to do some research now, find out just where this list comes from and how that is computed. Mind you, I'm not complaining, any list that hits Dean Koontz as #1 best seller is on target from what my dad has said about the guy's writing, but I'm curious just how they get these books as the best sellers. Are they really what people are buying, or what the publishers want the people to be buying? Did the marketing for each one make that much difference to it getting onto the list?

Anyone know where this has already all been answered? lol