Blurb Power: Does it Work?

For the first time in my career, I hesitantly approached a couple of my favorite bestselling YA authors, asking if they'd consider reading SECRET KEEPER and, if they liked it, sending me a quote that could be printed on the cover. Neither accepted my invitation -- politely, for perfectly valid reasons -- so the book will be blurb-free.

Then last week, I was approached by a first-time novelist to be quoted on her book. "I've got sweaty palms," she informed me in her email request, and I knew exactly how she felt. It was hard to ask.

Now I'm wondering -- can a validation from another author on the cover convince a reader to buy or borrow a book?