Is Obamacare a success? We might not know for a while

After months of focusing on how many people have or haven't signed up for health insurance under the Affordable Care Act, we now have a rough total (7.5 million), and everyone's keen to get to the bigger questions: How well is the law working? How many of those who signed up have paid their premiums and are actually getting coverage? How many were uninsured before they signed up? And just how big has the drop been in the number of uninsured people? Unfortunately, the answers to some of these questions simply aren't knowable — or, at least, not knowable yet.