Mark Lemley and Bhaven Sampat have released a new working paper that uses PAIR data to draw some conclusions about the current patent system:
Conclusion: The evidence illuminates the patent prosecution process as a continuing negotiation between examiner and applicant. That negotiation does not end with an initial or even a final rejection. Interviews and amendments after final play an extremely significant role in generating patents, and in limiting the scope of those claims as well. Nor is that the end of the process. Continuation applications are flourishing. They have broken into two roughly equal groups, with different uses. Many applicants are using RCEs to keep fighting for claims that the examiner wasn't willing to give them. The second group is filing continuation applications rather than RCEs. They have opted for a slower process, either because they want delay so that they can modify their application to track developments in the marketplace or because they want multiple patents to build an effective fence around a single invention.
In the paper, the authors implicitly retreat from earlier work criticizing the patent examination process –suggesting that their results here "may be a hopeful sign for patent examination: even though the PTO ultimately grants patents on a large majority of the applications it receives, it may still be serving an important gatekeeper function by requiring applicants to narrow their claims. (This assumes that most of those amendments narrow the claims; that seems likely, but we cannot test it empirically)."
Read the paper on SSRN.