Josh Barro demolishes this as another of Romney/Ryan’s distortions:

"The Romney campaign sent over a list of the studies, but they are perhaps more accurately described as 'analyses,' since four of them are blog posts or op-eds. I’m not hating — I blog for a living — but I don’t generally describe my posts as 'studies.'

"None of the analyses do what Romney’s campaign says: show that his tax plan is sound."