Which should be used to boost sales?

A recent study found that ebooks can boost print sales. Worthy of a study for sure, but in reality when the future is ebooks and electronic content, this would seem to be the wrong tactic. Why not offer free print books to increase ebook sales?

From the Digital Reader: Study shows that free ebooks boost print sales

A potential 30% minimum bump in sales would probably be welcome to the publishing industry. I’m all for a thriving industry that can support more authors and release more titles. Yet, to adopt this wide scale and expend great efforts to drive print sales with a tantalizing free ebook offer would negatively affect the perception of ebooks. Ebooks as weaker in sales and perfect freebies = perhaps profitable, surely not sustainable?

And, which is better for libraries?

Sometimes I have more questions than answers.